Reference intervals for serum creatinine for healthy adults in central Africa: a post-hoc analysis

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The present study aimed to establish such reference intervals from a healthy Congolese adult. Methods This study was based on post-hoc data of previous epidemiology study conducted in the general population of Kinshasa. Serum Creatinine measurement was performed with enzymatic IDMS-traceable method. The creatinine values being not normally distributed, the median values and interquartile range and the 2.5th and 97.5th percentiles were considered. A value of p < 0.05 is the threshold of statistical significance. Results Of 2,504 Congolese adults screened, 506 (males, 67.7%) were healthy and were involved in this study. Their mean BSA was 1.64 ± 0.15 m 2 . In males, the median of creatinine was 0.96 [0.87;1.05] mg/dl and percentiles 2.5th and 97.5th were 0.65 and 1.22 mg/dL, respectively. The reference intervals were between 0.65 (95%CI 0.68 to 0.72) and 1.23 (1.20 to 1.24) mg/dL for the lower and the upper limits, respectively. In females, the median of creatinine was 0.72 [0.66;0.80] mg/dl and percentiles 2.5th and 97.5th were 0.50 and 0.95 mg/dL, respectively. The reference intervals were between 0.52 (95%CI 0.50 to 0.54) and 0.95 (0.91 to 0.96) mg/dL for the lower and the upper limits respectively. Conclusion The reference intervals for Congolese adults seem close to these of White Europeans, with slightly higher values in Congolese compared to Caucasians, but lower than those of the African-Americans. serum creatinine Reference intervals adults central Africa Figures Figure 1 Figure 2 1. Background T he burden of chronic kidney disease (CKD) is shared by all regions of the world but particularly affects sub-Saharan African countries (SSA) [ 1 – 7 ]. Indeed, CKD is highly prevalent among 8–17% of the population [ 8 – 12 ]. In Democratic Republic of the Congo (DRC), the prevalence of CKD has been estimated at 12% [ 11 ]. In clinical practice, renal function is quantified using glomerular filtration rate (GFR) and GFR is mostly estimated by creatinine-based equations. Serum creatinine is thus widely used in patients who have blood tests measured routinely [ 13 – 15 ]. However, interpretation of serum creatinine results is not always easy. The serum creatinine concentration depends mainly on GFR but also on muscular mass. Therefore, for the same level of GFR, serum creatinine could be different according to age and sex. Also, serum creatinine has been shown to have different normal reference values, for example, between White and Black Americans, even if the mechanism explaining such a difference is not perfectly known [ 16 ]. Despite current interest in creatinine-based equations for estimating glomerular filtration rate (eGFR), the evaluation of creatinine reference intervals remains relevant. However, in the African population, those values are poorly documented. Most previous data have considered serum creatinine measured by the Jaffe method and most were not traceable to IDMS [ 17 – 19 ]. The present study aimed to determine the reference intervals of serum creatinine in a well-phenotyped population of healthy Congolese adults using an enzymatic IDMS traceable assay. 2. Methods 2.1. Study design, setting, and population This post-hoc analysis study is based on a larger epidemiological survey on CKD and associated risk factors, carried out between June 2015 and April 2016, in the general population of Kinshasa, capital of the DRC [ 20 ]. Sampling of the study of population has been described in detail elsewhere [ 20 ]. The study protocol was approved by the Ethics Committee of the Public Health School of the University of Kinshasa (N°ESP/CE/029/2015) and by the Institutional Review Boards at each site. Written informed consent was obtained from all participants, and all participants with abnormal findings received counseling and educational pamphlets. 2.2. Data collection All participants were visited twice at home by trained research personnel, who recorded information on demographics, diet, smoking, alcohol consumption, and use of indigenous herbal remedies. Familial medical history for kidney disease, hypertension, diabetes and current treatment were also recorded. The blood pressure was taken using an OMRON M3 Intellisense electronic blood pressure monitor (HEM-7051-E (V)). The body weight, height, waist and hip circumference were measured. The participants were screened for the absence of acute and chronic pathologies including hypertension, diabetes mellitus, obesity, cardiovascular diseases, known chronic kidney disease, and urinary abnormalities (proteinuria, hematuria or leucocyturia) by urine dipstick (“Combur10 Test”, Roche Diagnostics, Mannheim, Germany) on the morning urine. Capillary glycemia was measured for all participants, using a One-Touch Ultra brand glucometer. Medication was not allowed except for contraceptives in the female participants. Healthy participants did not have hypertension, diabetes mellitus, obesity, urinary abnormalities and known CKD. 2.2.1. Biochemical assays Five milliliters of venous blood were collected by venipuncture in 1 dry tube of 5 ml. Serum was separated by centrifugation at 3000 rpm within 10 min, samples were stored at -80°C and then were shipped to the clinical chemistry laboratory of the University of Liège (CHU de Liège) in Belgium which is ISO 151589 compliant. Creatinine measures were performed with the Roche Cobas (Roche Diagnostics, Mannheim, Germany) enzymatic method calibrated against the NIST SRM 967 whose concentration has been measured using the NIST LC/IDMS measurement procedurea. The coefficient of variation of the assay is < 2%. 2.3. Statistical analysis A minimum of 120 participants was required for each sex group, in line with the International Federation of Clinical Chemistry’s (IFCC) recommendations [ 21 ]. Data are expressed as mean ± standard deviation (SD) when distribution was normal and as median with interquartile range [quartile1; quartile 3] when not. Creatinine results were not normally distributed according to the Kolmogorov-Smirnov test, and therefore the median values, interquartile range and the 2.5th and 97.5th percentiles were considered. Continuous variables were compared between age / sex groups, using the Student t test, or Mann-Whitney U test as appropriate. Reference intervals were determined both in males and females using the Clinical and Laboratory Standards Institute (CLSI) guidelines for percentiles. Outliners were detected according to the Tukey test. We tested if reference interval were age-related by Altman & Chitty, and Wright & Royston [ 21 – 24 ]. We also studied the potential impact of clinical variables on serum creatinine concentrations. All analyses and calculations were performed using SAS 9.4 (SAS Institute Inc., Cary, NC, USA) and Medcalc (Mariakerke, Belgium). 3. Results 3.1. Population Two thousand five hundred and four Congolese adults were screened. Among them, 1,998 were excluded from the study because they had hypertension, diabetes mellitus, obesity, chronic kidney disease or urinary dipstick abnormalities, leaving 506 subjects considered as healthy for the analysis (Fig. 1 ). There were 343 men (68%) and 163 women (32%), aged between 19 and 80 years old with a mean age of 34.3 ± 12.8 years. Characteristics of the subjects are described in Table 1 . The mean height, weight, BSA and body mass index were 166.8 ± 9.0 cm, 57.7 ± 8.3 kg, 1.64 ± 0.15 m 2 and 20.7 ± 2.1 kg/m², respectively. Differences between men and women are also described in Table 1 . Table 1 General characteristics of study population Variables All n = 506 Males n = 343 Females n = 163 P value Age (years) 34.3 ± 12.8 35.5 ± 13.0 31.8 ± 11.9 0.003 Weight (kg) 57.7 ± 8.3 60.2 ± 7.9 52.3 ± 6.4 < 0.001 Height (cm) 166.8 ± 9.0 170.3 ± 7.7 159.4 ± 6.7 < 0.001 BSA (m 2 ) 1.60 ± 0.14 1.64 ± 0.13 1.51 ± 0.11 < 0.001 BMI (Kg/m 2 ) 20.7 ± 2.1 20.8 ± 2.2 20.6 ± 2.1 0.207 Waist (cm) 74.7 ± 6.0 75.8 ± 6.2 72.5 ± 4.8 < 0.001 Hip circum- ference (cm) 89.7 ± 5.6 89.6 ± 5.6 89.8 ± 5.7 0.314 SBP (mmHg) 119.7 ± 10.2 121.6 ± 9.5 115.7 ± 10.5 < 0.001 DBP (mmHg) 72.1 ± 7.9 73.3 ± 8.0 72.9 ± 7.7 0.298 MAP (mmHg) 88.7 ± 7.8 89.4 ± 7.7 87.1 ± 7.8 0.001 PP (mmHg) 46.5 ± 8.6 48.3 ± 8.1 42.8 ± 8.5 < 0.001 Creatinine (mg/dL) 0.88 ± 0.12 0.95 ± 0.14 0.73 ± 0.11 < 0.001 Fasting glycemia (mg/dL) 84.9 ± 12.6 84.5 ± 12.8 86.2 ± 11.7 0.265 Mean with SD, p < 0.05, abbreviations: BMI (Kg/m2): body mass index, BSA: Body surface area, DBP (mmHg): Diastolic blood pressure, MAP (mmHg): Mean blood pressure, PP (mmHg): pulse pressure, SBP (mmHg): Systolic blood pressure. 3.2 Reference Intervals Results are summarized in Table 2 . As expected, the median concentration of creatinine was higher in males 0.96 [0.86;1.05] mg/dl than in females 0.72 [0.66;0.80] mg/dL (p < 0.0001). In males, six creatinine values were excluded after applying the Tukey test. The median concentration was 0.96 [0.87;1.05] mg/dl and percentiles 2.5th and 97.5th were 0.65 and 1.22 mg/dL, respectively. The reference intervals were between 0.65 (95%CI 0.65 to 0.72) mg/dL for the lower limit and 1.23 (1.20 to 1.24) mg/dL for the upper limit. Reference intervals were not influenced by age (Fig. 2 ) for the men. In females, two creatinine values were excluded after applying the Tukey test. The median concentration was 0.72 [0.66;0.80] mg/dl and percentiles 2.5th and 97.5th were 0.50 and 0.95 mg/dL, respectively. The reference intervals were between 0.50 (95%CI 0.50 to 0.54) mg/dL for the lower limit and 0.95 (0.91 to 0.96) mg/dL for the upper limit. As observed in Fig. 2 . reference intervals were slightly influenced by age in females (p = 0.014) but no evidence for an age-dependency is observed in males. Table 2 Reference intervals for serum creatinine by gender Variables Creatinine (mg/dl) P Median (RI) 2.5th percentile (95% CI) 97.5th percentile (95% CI) Males : 343 0.96 (0.65–1.23) 0.65 (0.56–0.68) 1.22 (1.18–1.28) < 0.001 Females : 163 0.72 (0.52–0.95) 0.50 (0.42–0.56) 0.95 (0.93–0.99) Median (RI), p < 0.05, abbreviations: RI: Reference Interval; 95% CI, CI: confidence interval; 3.3. Determinants of creatinine in multiple linear regression Regarding the determinants of serum creatinine, the gender (p < 0.0001) and natural plants intake (p = 0.030) emerged in multivariate analysis as independent determinants of creatinine, as observed in Table 3 . Table 3. Determinants of creatinine in multiple linear regression Independent variables ꞵ SE t p (Intercept) -0.07 Age 0.00 0.00 1.77 0.077 Gender 0.17 0.02 9.22 <0.0001 Waist circumference 0.00 0.00 0.40 0.689 Hip circumference 0.00 0.00 0.54 0.586 Height 0.00 0.00 1.41 0.159 Sport -0.01 0.01 -0.63 0.528 Natural plant intake 0.03 0.01 2.17 0.030 Fruit intake 0.03 0.02 1.55 0.123 Pulse 0.00 0.00 -0.93 0.352 Weight 0.00 0.00 0.63 0.531 SBP 0.00 0.00 -0.33 0.743 Study level 0.01 0.01 1.17 0.245 Weekly walk 0.01 0.01 1.78 0.075 Arm circumference 0.01 0.00 1.67 0.096 R² = 0.409 p<0.05, abbreviations: SBP: Systolic blood pressure, 4. Discussion To our knowledge, this is the first study establishing the reference intervals for serum creatinine in Congolese adults. In line with the IFCC recommendations [ 21 ], serum creatinine was measured by an enzymatic method calibrated at IDMS. The reference intervals were 0.65 and 1.23 mg/dL and 0.50 and 0.95 mg/dL in males and females, respectively with median values of 0.96 mg/dL for males and 0.72 mg/dL for females. Reference intervals were slightly influenced by age in females (Fig. 2 ), but not in males. As expected, serum creatinine in men was higher than women in all age groups. These gender-related variations in serum creatinine were reported by several African and non-African studies. In 2000, a study in Kinshasa school setting, among adolescents aged 16 to 24, reported the percentiles 2.5th and 97.5th for serum creatinine of 0.66 and 1.26 mg / dL, respectively in males and 0.62 mg / dL and 1.43mg /dL, respectively in females [ 25 ]. In this previous Congolese study, serum creatinine was measured by Jaffe method not calibrated at IDMS. The discrepancy with the current results is probably analytical. It is well known that enzymatic creatinine is lower than results obtained with Jaffe method. However, the results change from one analyzer to another even if the same method is used [ 14 ]. This makes sense of standardizing creatinine results for all methods. Standardization of creatinine results improves the assessment of kidney function [ 26 ]. In Côte d’Ivoire (West Africa), a study was conducted by Yao et al in healthy subjects who donated blood, with serum creatinine assayed by a calibrated enzymatic method [ 27 ]. They reported serum creatinine values similar to the current study. The reference intervals for Congolese males and females seem close to the reference intervals of White Europeans males and females: [0.65–1.23 mg/dL] for males and [0.50–0.95 mg/dL] for females with median values of 0.96 mg/dL and 0.72 mg/dL respectively [ 26 ]. There is a slight difference in median values between Belgian and Congolese subjects: for males 0.96 mg/dL vs 0.90 mg/dL; for females 0.72 mg/dL versus 0.70 mg/l. In contrast, Congolese creatinine reference intervals were lower than those found in Cameroon by Edinga-Melenge et al ., These authors found a reference intervals serum creatinine of 0.74–1.36 mg / dL (P2.5-97.5th ) for males and 0.58–1.08 mg / dL (P2.5-97.5th ) for females[ 17 ]. American studies have reported higher serum creatinine reference ranges in the African American population compared to the white population [ 28 ]. The data from this study corroborate those from these different studies showing higher reference intervals for males than females in all age groups [ 17 ]. This variation would probably be linked to the difference in muscle mass between these different populations. Indeed, serum creatinine is the catabolite of muscle creatine which is synthesized mainly at the hepatic level. Daily, 1–2% of muscle creatine is converted into creatinine. It is obvious that the serum creatinine concentration is above all dependent on muscle mass. Thus, in the absence of any kidney disease, the differences in serum creatinine concentrations that can be observed between men and women, between old and young people, between different ethnic groups can be explained by differences in muscle mass [ 29 – 30 ]. However, this explanation remains hypothetical. The role of diet, notably the amount of meat, could also be important to explain such differences between populations. Further studies are still required. Comparing creatinine reference intervals across age groups, no influence of age was noted in males but a small influence of age was observed for females. This results must however interpreted with caution as the number of subjects older than 50 years old in our study is limited. Regarding the determinants of creatinine, the gender (p < 0.0001) and natural plant intake (p = 0.030) emerged in multivariate analysis. It has been found in several studies, including by Zinga et all. in DRC, that the natural plants intake was one of the causes of kidney failure and consequently of increased creatinine [ 31 ]. These results are potentially important for raising awareness of the kidney risk of natural plants intake, but further studies are necessary. 5. Conclusion For the first time, we established the reference intervals for Congolese males and females seem close to the reference intervals of White Europeans males and females, with slightly higher values. As expected, men have higher reference values than women. The gender and natural plants intake emerged as independent determinants of creatinine. Abbreviations BMI body mass index BSA Body surface area CKD chronic kidney disease CKD-EPI Chronic Kidney Disease Epidemiology CI Confidence interval CLSI Clinical & Laboratory Standards Institute DBP Diastolic blood pressure DRC Democratic Republic of the Congo FAS Full Age Spectrum GFR Glomerular filtration rate IDMS Isotope dilution mass spectrophotometry IFCC Federation of Clinical Chemistry’s IQR Interquartile range ISO International Organization for Standardization MAP Mean blood pressure NIST/ SRM National Institute of Standards and Technology / Standard Reference Material pp pulse pressure RI Reference interval SBP Systolic blood pressure SCr Serum creatinine SD standard deviation SSA Sub-saharian Africa Declarations Ethics approval and consent to participate The study was conducted with strict respect for human dignity. Data were collected on individual forms, anonymously and confidentially, in strict compliance with the Declaration of Helsinki. All aspects and procedures related to the study were explained to each potential participant. The study protocol was approved by the Ethics Committee of the School of Public Health, University of Kinshasa (N°ESP/CE/029/2015) and by the institutional evaluation committees of each site. Written informed consent was obtained in advance from all participants. Those with abnormal results received counseling and educational leaflets, and were managed at the nephrology unit of Kinshasa University Hospital. Availability of data and materials Data will be made available upon request addressed to the corresponding author. Conflict of Interest Statement The authors have no conflicts of interest to declare. Funding Sources This work received no funding Authors contributions Justine Bukabau, Ernest Sumaili and Pierre Delanaye conceived and designed the study. Justine Bukabau, Aliochia Nkodila, Pierre Delanaye, Hans Pottel, Ernest Sumaili, Etienne Cavalier and Jean-Robert Makulo analysed data, performed the statistical analysis and interpreted data. Justine Bukabau drafted the manuscript. Justine Bukabau, Ernest Sumaili, Pierre Delanaye, Etienne Cavalier, Hans Pottel, Jean-Robert Makulo, Vieux Mokoli, Aliochia Nkodila, François-Patanleon Kajingulu, Chantal Zinga, Augustin Longo, Yannick Engole, Yannick Nlandu, Marie-France Mboliasa and Nazaire Nseka revised the manuscript. All authors approved the final submitted version for publication and have agreed to be accountable for all aspects of the work. Acknowledgments We are most grateful to the Clinical Chemistry team of CHU of Liege. We thank all physicians and laboratory technicians who participated in the data collection for this study. In addition, we especially thank all the Congolese patients who consented to participate to this study. 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Semin Nephrol. 42(5):151319. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 30 Oct, 2025 Read the published version in BMC Nephrology → Version 1 posted Editorial decision: Revision requested 11 Jun, 2025 Reviews received at journal 09 Jun, 2025 Reviews received at journal 03 Jun, 2025 Reviewers agreed at journal 01 Jun, 2025 Reviews received at journal 29 May, 2025 Reviewers agreed at journal 20 May, 2025 Reviewers agreed at journal 10 May, 2025 Reviewers invited by journal 08 May, 2025 Editor invited by journal 07 May, 2025 Editor assigned by journal 06 May, 2025 Submission checks completed at journal 06 May, 2025 First submitted to journal 10 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6198894","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":454777422,"identity":"4902adf2-a03c-4c80-a725-436364154a4d","order_by":0,"name":"Justine Bukabau","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3ElEQVRIiWNgGAWjYBACxgYgkQBCPMwHIDwgTUgLYwNEC1sCRAuQJtIiHh4D4rQwz0h//uDhDps8gzNnvkn83GEjx8DG+wC/FTNyDBsSz6QVG5zt3SbZeybNmIGN3YCQFsaGxLbDiRvO826T4AUyGuTbCHhkRvpDoJb/QC08zyT/grSwsRHSkgB0WNuBxA1ne9ikeYnS0vPGcEZiW3Kx5JljxtaybWnGbIS0GLanP/j4s80uj+9M8sObb9ts5PgJamlAsFkkQCQBDQwM8khs5g+EVI+CUTAKRsHIBAAa4Uo0DpksNwAAAABJRU5ErkJggg==","orcid":"","institution":"University of Kinshasa","correspondingAuthor":true,"prefix":"","firstName":"Justine","middleName":"","lastName":"Bukabau","suffix":""},{"id":454777423,"identity":"6acb6b62-ddd1-4999-a2cf-432cae027510","order_by":1,"name":"Etienne Cavalier","email":"","orcid":"","institution":"University of Liège, CHU Sart Tilman","correspondingAuthor":false,"prefix":"","firstName":"Etienne","middleName":"","lastName":"Cavalier","suffix":""},{"id":454777424,"identity":"c917bfbd-49f2-43e9-a74a-679e21d31ab7","order_by":2,"name":"Hans Pottel","email":"","orcid":"","institution":"KU Leuven Campus Kulak Kortrijk","correspondingAuthor":false,"prefix":"","firstName":"Hans","middleName":"","lastName":"Pottel","suffix":""},{"id":454777425,"identity":"79ac5594-40a9-4978-b79e-09f90335e209","order_by":3,"name":"Aliocha Nkodila","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"Aliocha","middleName":"","lastName":"Nkodila","suffix":""},{"id":454777426,"identity":"f71f6d37-2c7b-41da-9a80-0c05c60558c5","order_by":4,"name":"Jean-Robert Makulo","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"Jean-Robert","middleName":"","lastName":"Makulo","suffix":""},{"id":454777427,"identity":"8ff16054-5abb-49a4-8c0a-64b4509fd93e","order_by":5,"name":"Vieux Mokoli","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"Vieux","middleName":"","lastName":"Mokoli","suffix":""},{"id":454777428,"identity":"59404edd-9610-447d-b016-470e08aad8bc","order_by":6,"name":"François-Patanleon Kajingulu","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"François-Patanleon","middleName":"","lastName":"Kajingulu","suffix":""},{"id":454777429,"identity":"d738c283-bdd9-4322-9c8f-982dfb338ba3","order_by":7,"name":"Chantal Zinga","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"Chantal","middleName":"","lastName":"Zinga","suffix":""},{"id":454777430,"identity":"a69f2b56-0fb7-4df7-a660-e149a8444e4b","order_by":8,"name":"Augustin Longo","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"Augustin","middleName":"","lastName":"Longo","suffix":""},{"id":454777431,"identity":"3cc0d8f0-827d-4546-bcb5-410c03717034","order_by":9,"name":"Yannick Engole","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"Yannick","middleName":"","lastName":"Engole","suffix":""},{"id":454777432,"identity":"cb85511d-ebf2-4b81-bb31-5061965d4481","order_by":10,"name":"Yannick Nlandu","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"Yannick","middleName":"","lastName":"Nlandu","suffix":""},{"id":454777433,"identity":"490cef8d-7225-4c44-ad24-1fa1ce6d6150","order_by":11,"name":"Marie-France Mboliasa","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"Marie-France","middleName":"","lastName":"Mboliasa","suffix":""},{"id":454777434,"identity":"b8403c3c-a23a-4a18-914d-34571a958ad1","order_by":12,"name":"Nazaire Nseka","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"Nazaire","middleName":"","lastName":"Nseka","suffix":""},{"id":454777435,"identity":"c55033b3-204f-460a-8ab0-cd1dbcf1ffe4","order_by":13,"name":"Pierre Delanaye","email":"","orcid":"","institution":"University of Liège, CHU Sart Tilman","correspondingAuthor":false,"prefix":"","firstName":"Pierre","middleName":"","lastName":"Delanaye","suffix":""},{"id":454777436,"identity":"0562a883-b8a2-48d4-8a06-e3b073959faa","order_by":14,"name":"Ernest Sumaili","email":"","orcid":"","institution":"University of Kinshasa","correspondingAuthor":false,"prefix":"","firstName":"Ernest","middleName":"","lastName":"Sumaili","suffix":""}],"badges":[],"createdAt":"2025-03-10 23:38:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6198894/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6198894/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12882-025-04538-w","type":"published","date":"2025-10-30T15:57:03+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":82597115,"identity":"59411993-98ed-4b22-8d51-4bab43b9d85b","added_by":"auto","created_at":"2025-05-13 08:55:47","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":27329,"visible":true,"origin":"","legend":"\u003cp\u003eFlow diagram of the study population\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6198894/v1/7e449c08b6e717f9847e9628.png"},{"id":82597116,"identity":"9bf8f10b-a89d-4998-a215-6eaf1becbe7d","added_by":"auto","created_at":"2025-05-13 08:55:47","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":261229,"visible":true,"origin":"","legend":"\u003cp\u003eAge related reference intervals of creatinine by gender.\u003c/p\u003e\n\u003cp\u003ea. Age related reference intervals of creatinine for Males\u003c/p\u003e\n\u003cp\u003eb. Age related reference intervals of creatinine of Females\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6198894/v1/945c4cf42f936231b9831566.png"},{"id":95039840,"identity":"b8f9b26d-3ea6-40e5-9688-79d5dcd11776","added_by":"auto","created_at":"2025-11-03 16:04:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1146148,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6198894/v1/a1d46a03-dede-4650-ab5b-d7cebd3472e4.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Reference intervals for serum creatinine for healthy adults in central Africa: a post-hoc analysis","fulltext":[{"header":"1. Background","content":"\u003cp\u003e \u003cb\u003eT\u003c/b\u003ehe burden of chronic kidney disease (CKD) is shared by all regions of the world but particularly affects sub-Saharan African countries (SSA) [\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5 CR6\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Indeed, CKD is highly prevalent among 8\u0026ndash;17% of the population [\u003cspan additionalcitationids=\"CR9 CR10 CR11\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In Democratic Republic of the Congo (DRC), the prevalence of CKD has been estimated at 12% [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. In clinical practice, renal function is quantified using glomerular filtration rate (GFR) and GFR is mostly estimated by creatinine-based equations. Serum creatinine is thus widely used in patients who have blood tests measured routinely [\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. However, interpretation of serum creatinine results is not always easy. The serum creatinine concentration depends mainly on GFR but also on muscular mass. Therefore, for the same level of GFR, serum creatinine could be different according to age and sex. Also, serum creatinine has been shown to have different normal reference values, for example, between White and Black Americans, even if the mechanism explaining such a difference is not perfectly known [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Despite current interest in creatinine-based equations for estimating glomerular filtration rate (eGFR), the evaluation of creatinine reference intervals remains relevant. However, in the African population, those values are poorly documented. Most previous data have considered serum creatinine measured by the Jaffe method and most were not traceable to IDMS [\u003cspan additionalcitationids=\"CR18\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The present study aimed to determine the reference intervals of serum creatinine in a well-phenotyped population of healthy Congolese adults using an enzymatic IDMS traceable assay.\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Study design, setting, and population\u003c/h2\u003e \u003cp\u003eThis \u003cem\u003epost-hoc\u003c/em\u003e analysis study is based on a larger epidemiological survey on CKD and associated risk factors, carried out between June 2015 and April 2016, in the general population of Kinshasa, capital of the DRC [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Sampling of the study of population has been described in detail elsewhere [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The study protocol was approved by the Ethics Committee of the Public Health School of the University of Kinshasa (N\u0026deg;ESP/CE/029/2015) and by the Institutional Review Boards at each site. Written informed consent was obtained from all participants, and all participants with abnormal findings received counseling and educational pamphlets.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Data collection\u003c/h2\u003e \u003cp\u003eAll participants were visited twice at home by trained research personnel, who recorded information on demographics, diet, smoking, alcohol consumption, and use of indigenous herbal remedies. Familial medical history for kidney disease, hypertension, diabetes and current treatment were also recorded. The blood pressure was taken using an OMRON M3 Intellisense electronic blood pressure monitor (HEM-7051-E (V)). The body weight, height, waist and hip circumference were measured. The participants were screened for the absence of acute and chronic pathologies including hypertension, diabetes mellitus, obesity, cardiovascular diseases, known chronic kidney disease, and urinary abnormalities (proteinuria, hematuria or leucocyturia) by urine dipstick (\u0026ldquo;Combur10 Test\u0026rdquo;, Roche Diagnostics, Mannheim, Germany) on the morning urine. Capillary glycemia was measured for all participants, using a One-Touch Ultra brand glucometer. Medication was not allowed except for contraceptives in the female participants. Healthy participants did not have hypertension, diabetes mellitus, obesity, urinary abnormalities and known CKD.\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1. Biochemical assays\u003c/h2\u003e \u003cp\u003eFive milliliters of venous blood were collected by venipuncture in 1 dry tube of 5 ml. Serum was separated by centrifugation at 3000 rpm within 10 min, samples were stored at -80\u0026deg;C and then were shipped to the clinical chemistry laboratory of the University of Li\u0026egrave;ge (CHU de Li\u0026egrave;ge) in Belgium which is ISO 151589 compliant. Creatinine measures were performed with the Roche Cobas (Roche Diagnostics, Mannheim, Germany) enzymatic method calibrated against the NIST SRM 967 whose concentration has been measured using the NIST LC/IDMS measurement procedurea. The coefficient of variation of the assay is \u0026lt;\u0026thinsp;2%.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Statistical analysis\u003c/h2\u003e \u003cp\u003eA minimum of 120 participants was required for each sex group, in line with the International Federation of Clinical Chemistry\u0026rsquo;s (IFCC) recommendations [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Data are expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD) when distribution was normal and as median with interquartile range [quartile1; quartile 3] when not. Creatinine results were not normally distributed according to the Kolmogorov-Smirnov test, and therefore the median values, interquartile range and the 2.5th and 97.5th percentiles were considered. Continuous variables were compared between age / sex groups, using the Student t test, or Mann-Whitney U test as appropriate. Reference intervals were determined both in males and females using the Clinical and Laboratory Standards Institute (CLSI) guidelines for percentiles. Outliners were detected according to the Tukey test. We tested if reference interval were age-related by Altman \u0026amp; Chitty, and Wright \u0026amp; Royston [\u003cspan additionalcitationids=\"CR22 CR23\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWe also studied the potential impact of clinical variables on serum creatinine concentrations. All analyses and calculations were performed using SAS 9.4 (SAS Institute Inc., Cary, NC, USA) and Medcalc (Mariakerke, Belgium).\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Population\u003c/h2\u003e \u003cp\u003eTwo thousand five hundred and four Congolese adults were screened. Among them, 1,998 were excluded from the study because they had hypertension, diabetes mellitus, obesity, chronic kidney disease or urinary dipstick abnormalities, leaving 506 subjects considered as healthy for the analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). There were 343 men (68%) and 163 women (32%), aged between 19 and 80 years old with a mean age of 34.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12.8 years. Characteristics of the subjects are described in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The mean height, weight, BSA and body mass index were 166.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.0 cm, 57.7\u0026thinsp;\u0026plusmn;\u0026thinsp;8.3 kg, 1.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15 m\u003csup\u003e2\u003c/sup\u003e and 20.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 kg/m\u0026sup2;, respectively. Differences between men and women are also described in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eGeneral characteristics of study population\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAll\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;506\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMales\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;343\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFemales\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;163\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge (years)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e34.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e35.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e31.8\u0026thinsp;\u0026plusmn;\u0026thinsp;11.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eWeight (kg)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e57.7\u0026thinsp;\u0026plusmn;\u0026thinsp;8.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e60.2\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e52.3\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHeight (cm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e166.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e170.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e159.4\u0026thinsp;\u0026plusmn;\u0026thinsp;6.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBSA (m\u003c/b\u003e\u003csup\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sup\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e1.51\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBMI (Kg/m\u003c/b\u003e\u003csup\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sup\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e20.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e20.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e20.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.207\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eWaist (cm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e74.7\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e75.8\u0026thinsp;\u0026plusmn;\u0026thinsp;6.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e72.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHip circum-\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003eference (cm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e89.7\u0026thinsp;\u0026plusmn;\u0026thinsp;5.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e89.6\u0026thinsp;\u0026plusmn;\u0026thinsp;5.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e89.8\u0026thinsp;\u0026plusmn;\u0026thinsp;5.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.314\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSBP (mmHg)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e119.7\u0026thinsp;\u0026plusmn;\u0026thinsp;10.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e121.6\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e115.7\u0026thinsp;\u0026plusmn;\u0026thinsp;10.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDBP (mmHg)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e72.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e73.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e72.9\u0026thinsp;\u0026plusmn;\u0026thinsp;7.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.298\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMAP (mmHg)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e88.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e89.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e87.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePP (mmHg)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e46.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e48.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e42.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCreatinine (mg/dL)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFasting glycemia (mg/dL)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e84.9\u0026thinsp;\u0026plusmn;\u0026thinsp;12.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e84.5\u0026thinsp;\u0026plusmn;\u0026thinsp;12.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e86.2\u0026thinsp;\u0026plusmn;\u0026thinsp;11.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.265\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003eMean with SD, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05, abbreviations: BMI (Kg/m2): body mass index, BSA: Body surface area, DBP (mmHg): Diastolic blood pressure, MAP (mmHg): Mean blood pressure, PP (mmHg): pulse pressure, SBP (mmHg): Systolic blood pressure.\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003e3.2 Reference Intervals\u003c/b\u003e \u003c/p\u003e \u003cp\u003eResults are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. As expected, the median concentration of creatinine was higher in males 0.96 [0.86;1.05] mg/dl than in females 0.72 [0.66;0.80] mg/dL (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). In males, six creatinine values were excluded after applying the Tukey test. The median concentration was 0.96 [0.87;1.05] mg/dl and percentiles 2.5th and 97.5th were 0.65 and 1.22 mg/dL, respectively. The reference intervals were between 0.65 (95%CI 0.65 to 0.72) mg/dL for the lower limit and 1.23 (1.20 to 1.24) mg/dL for the upper limit. Reference intervals were not influenced by age (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) for the men. In females, two creatinine values were excluded after applying the Tukey test. The median concentration was 0.72 [0.66;0.80] mg/dl and percentiles 2.5th and 97.5th were 0.50 and 0.95 mg/dL, respectively. The reference intervals were between 0.50 (95%CI 0.50 to 0.54) mg/dL for the lower limit and 0.95 (0.91 to 0.96) mg/dL for the upper limit. As observed in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. reference intervals were slightly influenced by age in females (p\u0026thinsp;=\u0026thinsp;0.014) but no evidence for an age-dependency is observed in males.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eReference intervals for serum creatinine by gender\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eCreatinine (mg/dl)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMedian\u003c/p\u003e \u003cp\u003e(RI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.5th percentile\u003c/p\u003e \u003cp\u003e(95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e97.5th percentile\u003c/p\u003e \u003cp\u003e(95% CI)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMales\u0026nbsp;: 343\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.96 (0.65\u0026ndash;1.23)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.65 (0.56\u0026ndash;0.68)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.22 (1.18\u0026ndash;1.28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFemales\u0026nbsp;: 163\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.72 (0.52\u0026ndash;0.95)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.50 (0.42\u0026ndash;0.56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.95 (0.93\u0026ndash;0.99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003eMedian (RI), p\u0026thinsp;\u0026lt;\u0026thinsp;0.05, abbreviations: RI: Reference Interval; 95% CI, CI: confidence interval;\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Determinants of creatinine in multiple linear regression\u003c/h2\u003e \u003cp\u003eRegarding the determinants of serum creatinine, the gender (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) and natural plants intake (p\u0026thinsp;=\u0026thinsp;0.030) emerged in multivariate analysis as independent determinants of creatinine, as observed in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e\u0026nbsp;\u003cstrong\u003eTable 3. Determinants of creatinine in multiple linear regression\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable style=\"border-collapse: collapse;border: none;width: 631px;\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 8.85pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;line-height: 200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eIndependent\u0026nbsp;variables\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 8.85pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eꞵ\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.8pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 8.85pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eSE\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 8.85pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003et\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 8.85pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 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style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan 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style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e1.77\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.077\u003c/span\u003e\u003c/p\u003e\n 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78.8pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.02\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e9.22\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;color:red;\"\u003e\u0026lt;0.0001\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eWaist circumference\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n 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style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.40\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.689\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eHip circumference\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.8pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.54\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.586\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eHeight\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.8pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e1.41\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.159\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 12.55pt;vertical-align: top;\"\u003e\n \u003cp 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style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.01\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 12.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e-0.63\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 12.55pt;vertical-align: top;\"\u003e\n \u003cp 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style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e2.17\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;color:red;\"\u003e0.030\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 9.2pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eFruit intake\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border: none;padding: 0in 5.4pt;height: 9.2pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.03\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.8pt;border: none;padding: 0in 5.4pt;height: 9.2pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.02\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 9.2pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e1.55\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 9.2pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.123\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003ePulse\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.8pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e-0.93\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.352\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eWeight\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.8pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.63\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.531\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eSBP\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.8pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e-0.33\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 15.25pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.743\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 16.6pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eStudy level\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border: none;padding: 0in 5.4pt;height: 16.6pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.01\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.8pt;border: none;padding: 0in 5.4pt;height: 16.6pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.01\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 16.6pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e1.17\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 16.6pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.245\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eWeekly walk\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.01\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.8pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.01\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e1.78\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.075\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003eArm circumference\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96.45pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.01\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.8pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.00\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.85pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e1.67\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78.95pt;border: none;padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.0pt;line-height:200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e0.096\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 140.2pt;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid rgb(127, 127, 127);padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;text-indent: 12.05pt;line-height:200%;'\u003e\u003cstrong\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e\u0026nbsp;\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 333.05pt;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid rgb(127, 127, 127);padding: 0in 5.4pt;height: 2.55pt;vertical-align: top;\"\u003e\n \u003cp style='margin-top:0in;margin-right:0in;margin-bottom:0in;margin-left:0in;font-size:11.0pt;font-family:\"Calibri\",sans-serif;text-align:justify;line-height: 200%;'\u003e\u003cspan style=\"font-size:16px;line-height:200%;font-family:Calibri;\"\u003e\u0026nbsp; \u0026nbsp;R\u0026sup2; = 0.409\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\u003cp\u003e\u003cem\u003ep\u0026lt;0.05, abbreviations: SBP: Systolic blood pressure,\u0026nbsp;\u003c/em\u003e\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eTo our knowledge, this is the first study establishing the reference intervals for serum creatinine in Congolese adults. In line with the IFCC recommendations [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], serum creatinine was measured by an enzymatic method calibrated at IDMS. The reference intervals were 0.65 and 1.23 mg/dL and 0.50 and 0.95 mg/dL in males and females, respectively with median values of 0.96 mg/dL for males and 0.72 mg/dL for females. Reference intervals were slightly influenced by age in females (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), but not in males.\u003c/p\u003e \u003cp\u003eAs expected, serum creatinine in men was higher than women in all age groups. These gender-related variations in serum creatinine were reported by several African and non-African studies. In 2000, a study in Kinshasa school setting, among adolescents aged 16 to 24, reported the percentiles 2.5th and 97.5th for serum creatinine of 0.66 and 1.26 mg / dL, respectively in males and 0.62 mg / dL and 1.43mg /dL, respectively in females [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this previous Congolese study, serum creatinine was measured by Jaffe method not calibrated at IDMS. The discrepancy with the current results is probably analytical.\u003c/p\u003e \u003cp\u003eIt is well known that enzymatic creatinine is lower than results obtained with Jaffe method. However, the results change from one analyzer to another even if the same method is used [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. This makes sense of standardizing creatinine results for all methods. Standardization of creatinine results improves the assessment of kidney function [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn C\u0026ocirc;te d\u0026rsquo;Ivoire (West Africa), a study was conducted by Yao \u003cem\u003eet al\u003c/em\u003e in healthy subjects who donated blood, with serum creatinine assayed by a calibrated enzymatic method [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. They reported serum creatinine values similar to the current study. The reference intervals for Congolese males and females seem close to the reference intervals of White Europeans males and females: [0.65\u0026ndash;1.23 mg/dL] for males and [0.50\u0026ndash;0.95 mg/dL] for females with median values of 0.96 mg/dL and 0.72 mg/dL respectively [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. There is a slight difference in median values between Belgian and Congolese subjects: for males 0.96 mg/dL vs 0.90 mg/dL; for females 0.72 mg/dL versus 0.70 mg/l.\u003c/p\u003e \u003cp\u003eIn contrast, Congolese creatinine reference intervals were lower than those found in Cameroon by Edinga-Melenge \u003cem\u003eet al\u003c/em\u003e., These authors found a reference intervals serum creatinine of 0.74\u0026ndash;1.36 mg / dL (P2.5-97.5th ) for males and 0.58\u0026ndash;1.08 mg / dL (P2.5-97.5th ) for females[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. American studies have reported higher serum creatinine reference ranges in the African American population compared to the white population [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe data from this study corroborate those from these different studies showing higher reference intervals for males than females in all age groups [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis variation would probably be linked to the difference in muscle mass between these different populations. Indeed, serum creatinine is the catabolite of muscle creatine which is synthesized mainly at the hepatic level. Daily, 1\u0026ndash;2% of muscle creatine is converted into creatinine. It is obvious that the serum creatinine concentration is above all dependent on muscle mass. Thus, in the absence of any kidney disease, the differences in serum creatinine concentrations that can be observed between men and women, between old and young people, between different ethnic groups can be explained by differences in muscle mass [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. However, this explanation remains hypothetical. The role of diet, notably the amount of meat, could also be important to explain such differences between populations. Further studies are still required.\u003c/p\u003e \u003cp\u003eComparing creatinine reference intervals across age groups, no influence of age was noted in males but a small influence of age was observed for females. This results must however interpreted with caution as the number of subjects older than 50 years old in our study is limited.\u003c/p\u003e \u003cp\u003eRegarding the determinants of creatinine, the gender (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) and natural plant intake (p\u0026thinsp;=\u0026thinsp;0.030) emerged in multivariate analysis. It has been found in several studies, including by Zinga et all. in DRC, that the natural plants intake was one of the causes of kidney failure and consequently of increased creatinine [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. These results are potentially important for raising awareness of the kidney risk of natural plants intake, but further studies are necessary.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eFor the first time, we established the reference intervals for Congolese males and females seem close to the reference intervals of White Europeans males and females, with slightly higher values. As expected, men have higher reference values than women. The gender and natural plants intake emerged as independent determinants of creatinine.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBMI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ebody mass index\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBSA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBody surface area\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCKD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003echronic kidney disease\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCKD-EPI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eChronic Kidney Disease Epidemiology\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eConfidence interval\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCLSI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eClinical \u0026amp; Laboratory Standards Institute\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDBP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDiastolic blood pressure\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDRC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDemocratic Republic of the Congo\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eFAS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eFull Age Spectrum\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eGFR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eGlomerular filtration rate\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIDMS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eIsotope dilution mass spectrophotometry\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIFCC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eFederation of Clinical Chemistry\u0026rsquo;s\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIQR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInterquartile range\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eISO\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInternational Organization for Standardization\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMAP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMean blood pressure\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eNIST/ SRM\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNational Institute of Standards and Technology / Standard Reference Material\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003epp\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003epulse pressure\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eReference interval\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSBP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSystolic blood pressure\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSCr\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSerum creatinine\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003estandard deviation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSSA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSub-saharian Africa\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was conducted with strict respect for human dignity. Data were collected on individual forms, anonymously and confidentially, in strict compliance with the Declaration of Helsinki. All aspects and procedures related to the study were explained to each potential participant. The study protocol was approved by the Ethics Committee of the School of Public Health, University of Kinshasa (N°ESP/CE/029/2015) and by the institutional evaluation committees of each site. Written informed consent was obtained in advance from all participants. Those with abnormal results received counseling and educational leaflets, and were managed at the nephrology unit of Kinshasa University Hospital.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData will be made available upon request addressed to the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no conflicts of interest to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Sources\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work received no funding\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJustine Bukabau, Ernest Sumaili and Pierre Delanaye conceived and designed the study. \u0026nbsp;Justine Bukabau, Aliochia Nkodila, Pierre Delanaye, Hans Pottel, Ernest Sumaili, Etienne Cavalier and Jean-Robert Makulo analysed data, performed the statistical analysis and interpreted data. Justine Bukabau drafted the manuscript. \u0026nbsp;Justine Bukabau, Ernest Sumaili, Pierre Delanaye, Etienne Cavalier, Hans Pottel, Jean-Robert Makulo, Vieux Mokoli, Aliochia Nkodila, François-Patanleon Kajingulu, Chantal Zinga, Augustin Longo, Yannick Engole, Yannick Nlandu, Marie-France Mboliasa and Nazaire Nseka revised the manuscript. All authors approved the final submitted version for publication and have agreed to be accountable for all aspects of the work.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe are most grateful to the Clinical Chemistry team of CHU of Liege. We thank all physicians and laboratory technicians who participated in the data collection for this study. In addition, we especially thank all the Congolese patients who consented to participate to this study.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGeorge c, stoker s, okpechi i, woodward m, kengne A George C et al. The Chronic Kidney Disease in Africa (CKD-Africa) collaboration: lessons from a new pan-African network. CKD-Africa Collaboration. BMJ Glob Health 2021. 6(8):e006454. \u003c/li\u003e\n\u003cli\u003eNestor-M Pakasa 1 , Ernest-K Suma\u0026iuml;li, [Pathological peculiarities of chronic kidney disease in patient from sub-Saharan Africa. Review of data from the Democratic Republic of the Congo]. Ann Pathol 2012. 32(1): 40- 52 \u003c/li\u003e\n\u003cli\u003eMuiru AN, Charlebois ED, Balzer LB, Kwarisiima D, Elly A, Black D et al. The epidemiology of chronic kidney disease (CKD) in rural East Africa: A population-based study. PLoS One 2020. 4;15(3): e0229649.\u003c/li\u003e\n\u003cli\u003eOvwasa H, Aiwuyo HO, Okoye A OC, Unuigbe E, Rajora N. Epidemiology Trend of Chronic Kidney Disease in a Semi-Urban Tertiary Hospital in Sub-Saharan Africa. Cureus. 2023 30;15(3): e36912. \u003c/li\u003e\n\u003cli\u003eLiyanage T, Toyama T, Hockham C, Ninomiya T, Perkovic V, Woodward M, Fukagawa M, Matsushita K, Praditpornsilpa K, Hooi LS, Iseki K, Lin MY, Stirnadel-Farrant HA, Jha V, Jun M. Prevalence of chronic kidney disease in Asia: a systematic review and analysis. BMJ Glob Health. 20227(1):e007525. \u003c/li\u003e\n\u003cli\u003eEvans M, Lewis RD, Morgan AR, Whyte MB, Hanif W, Bain SC, Davies S, Dashora U, Yousef Z, Patel DC, Strain WD, 2022. A Narrative Review of Chronic Kidney Disease in Clinical Practice: Current Challenges and Future Perspectives. Adv Ther. 39(1):33-43. \u003c/li\u003e\n\u003cli\u003eTangri N, Moriyama T, Schneider MP, Virgitti JB, De Nicola L, Arnold M, Barone S, Peach E, Wittbrodt E, Chen H, J\u0026auml;rbrink K, Kushner P, 2023. Prevalence of undiagnosed stage 3 chronic kidney disease in France, Germany, Italy, Japan and the USA: results from the multinational observational REVEAL-CKD study. BMJ Open. 22;13(5):e067386. \u003c/li\u003e\n\u003cli\u003eWang L, Xu X, Zhang M, Hu C, Zhang X, Li C, Nie S, Huang Z, Zhao Z, Hou FF, Zhou M, 2023. Prevalence of Chronic Kidney Disease in China: Results From the Sixth China Chronic Disease and Risk Factor Surveillance. JAMA Intern Med. 1;183(4):298-310.\u003c/li\u003e\n\u003cli\u003eMarc G Vervloet , Hilda Ji de Jong , Jan Pander , Jetty A Overbeek, 2023. Prevalence of chronic kidney disease in the Netherlands and its cardiovascular and renal complications. BMC Nephrol. 13;24(1):337. \u003c/li\u003e\n\u003cli\u003eFrancois Folefack Kaze , Mahamat Maimouna , Augustin Fanday Beybey , Eric Walter Pefura-Yone , Adamou Dodo Balkissou , Marie Patrice Halle , Mathurin Pierre Kowo , Gloria Ashuntantang , Andre-Pascal Kengne, 2021. Prevalence and determinants of chronic kidney disease in urban adults\u0026apos; populations of northern Cameroon. Clin Exp Nephrol. 25(7):718-726.\u003c/li\u003e\n\u003cli\u003eBr\u0026uuml;ck K, Stel VS, Gambaro G, Hallan S, V\u0026ouml;lzke H, \u0026Auml;rnl\u0026ouml;v J, Kastarinen M, Guessous I, Vinhas J, Stengel B, Brenner H, Chudek J, Romundstad S, Tomson C, Gonzalez AO, Bello AK, Ferrieres J, Palmieri L, Browne G, Capuano V, Van Biesen W, Zoccali C, Gansevoort R, Navis G, Rothenbacher D, Ferraro PM, Nitsch D, Wanner C, Jager KJ, 2016. CKD Prevalence Varies across the European General Population. European CKD Burden Consortium. J Am Soc Nephrol. 27(7):2135-47.\u003c/li\u003e\n\u003cli\u003eErnest K Sumaili , Jean-Marie Krzesinski, Chantal V Zinga, Eric P Cohen, Pierre Delanaye, Sylvain M Munyanga, Nazaire M Nseka, 2009. Prevalence of chronic kidney disease in Kinshasa: results of a pilot study from the Democratic Republic of Congo. Nephrol Dial Transplant. 24(1):117-22.\u003c/li\u003e\n\u003cli\u003eSpencer S, Desborough R, Bhandari S, 2023. Should Cystatin C eGFR Become Routine Clinical Practice? Biomolecules. 5;13(7):1075. 12. \u003c/li\u003e\n\u003cli\u003eDelanaye P, Cavalier E, Maillard N, Krzesinski JM, Mariat C, Cristol JP, Laurence Pi\u0026eacute;roni, 2010. [Creatinine: past and present]. Ann Biol Clin. 68 (5):531-43. 13.\u003c/li\u003e\n\u003cli\u003eDelanaye P, Cavalier E, Mariat C, Maillard N, Dubois BE, Krzesinski JM, 2009. [Detection and estimation of chronic kidney disease]. Rev Med Liege. 64 (2):73-8.\u003c/li\u003e\n\u003cli\u003eP. Delanaye, J-M. Krzesinski, 2014. Evaluation of glomerular filtration rate in 2014 Rev Med Li\u0026egrave;ge. 69: 47-52.\u003c/li\u003e\n\u003cli\u003eBertille Elodie Edinga-Melenge, Adrienne Tchapmi Yakam , Jobert Richie Nansseu , Catherine Bilong , Suzanne Belinga , Eric Minkala , Prisca Armel Noudjeu , Michel Ondhoua , Samuel Walter Kokola , Vicky Joceline Ama Moor, Gloria Ashuntantang, 2019. Reference intervals for serum cystatin C and serum creatinine in an adult sub-Saharan African population. BMC Clin Pathol.18:19:4.\u003c/li\u003e\n\u003cli\u003eYayo E, Aye M, Yao C, Gnionsahe A, Attoungbre ML, Cavalier E, Pottel H , Monnet Dagui, Delanaye P, 2018. Measured (and estimated) glomerular filtration rate: reference values in West Africa. Nephrol Dial Transplant. 33 (7): 1176-1180. \u003c/li\u003e\n\u003cli\u003ePierre Delanaye, Etienne Cavalier, Thomas Stehl\u0026eacute;, Hans Pottel, 2024. Glomerular Filtration Rate Estimation in Adults: Myths and Promises. Nephron.148(6):408-414.\u003c/li\u003e\n\u003cli\u003eBukabau JB, Sumaili EK, Cavalier E, Pottel H, Kifakiou B, Nkodila A, Makulo JRR, Mokoli VM, Zinga CV, Longo AL, Engole YM, Nlandu YM, Lepira FB, Nseka NM, Krzesinski JM, Delanaye P, 2018. Performance of glomerular filtration rate estimation equations in Congolese healthy adults: The inopportunity of the ethnic correction. PLoS One. 2;13(3):e0193384.\u003c/li\u003e\n\u003cli\u003eClinical Laboratory Standards Institute, 2008. Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Proposed Guideline. Proposed Guideline. C28-P3. \u003c/li\u003e\n\u003cli\u003eKevin Le Boedec, 2019. Reference interval estimation of small sample sizes: A methodologic comparison using a computer-simulation study. Vet Clin Pathol, 48(2):335-346.\u003c/li\u003e\n\u003cli\u003eD G Altman, L S Chitty, 1997. New charts for ultrasound dating of pregnancy. Ultrasound Obstet Gynecol. 10(3):174-91.\u003c/li\u003e\n\u003cli\u003eE M Wright, P Royston, 1997. Simplified estimation of age-specific reference intervals for skewed data. Stat Med. 30;16(24):2785-803.\u003c/li\u003e\n\u003cli\u003eBukabau JB, Makulo JR, Pakasa NM, Cohen EP, Lepira FB, Kayembe PK, Nseka NM, Sumaili EK, 2012. Chronic kidney disease among high school students of Kinshasa. BMC Nephrol . 13:24.\u003c/li\u003e\n\u003cli\u003eHans Pottel, Etienne Cavalier, Jonas Bj\u0026ouml;rk, Ulf Nyman, Anders Grubb, Natalie Ebert, Elke Schaeffner, Bj\u0026ouml;rn O. Eriksen, Toralf Melsom, Edmund J. Lamb, Christophe Mariat, Laurence Dubourg, Magnus Hansson, Karin Littmann, Per-Ola Sundin, Anna \u0026Aring;kesson, Anders Larsson, Andrew Rule and Pierre Delanaye, 2022. Standardization of serum creatinine is essential for accurate use of unbiased estimated GFR equations: evidence from three cohorts matched on renal function. Clinical Kidney Journal 15; 12, 2258\u0026ndash;2265.\u003c/li\u003e\n\u003cli\u003eYayo E, Aye M, Yao C, Gnionsahe A, Attoungbre ML, Cavalier E, Pottel H, Monnet D, Delanaye P, 2018. Measured (and estimated) glomerular filtration rate: reference values in West Africa. Nephrol Dial Transplant. 33 (7): 1176-1180.\u003c/li\u003e\n\u003cli\u003eEric Sagou Yayo, Mireille Aye, Jean-Louis Konan, Arlette Emi\u0026egrave;me, Marie-Laure Attoungbre , Appolinaire Gnionsahe\u0026acute; , Etienne Cavalier, Dagui Monnet a, Pierre Delanaye, 2016. Inadequacy of the African-American ethnic factor to estimate glomerular filtration rate in an African general population: Results from C\u0026ocirc;te d\u0026rsquo;Ivoire. N\u0026eacute;phrologie \u0026amp; Th\u0026eacute;rapeutique. 12 ; 454\u0026ndash;459\u003c/li\u003e\n\u003cli\u003eBarbour GL, Crumb CK, Boyd CM, Reeves RD, Rastogi SP, Patterson RM, 1976. Comparison of inulin, iothalamate, and 99mTc-DTPA for measurement of glomerular filtration rate. J Nucl Med. 17 (4):317-20.\u003c/li\u003e\n\u003cli\u003ePasala S, Carmody JB, 2017. How to use... serum creatinine, cystatin C and GFR. Arch Dis Child Educ Pract Ed. 102 (1):37-43 \u003c/li\u003e\n\u003cli\u003eZinga C, Taba K, Mesia G, Sumaili E, Tona G, Muyembe JJ, Kindala J, Nseka N, 2022. Use of Medicinal Plants in Africa: A Case Study from the Democratic Republic of Congo (DRC). Semin Nephrol. 42(5):151319.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-nephrology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bnep","sideBox":"Learn more about [BMC Nephrology](http://bmcnephrol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bnep/default.aspx","title":"BMC Nephrology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"serum creatinine, Reference intervals, adults, central Africa","lastPublishedDoi":"10.21203/rs.3.rs-6198894/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6198894/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eDespite current interest in creatinine-based equations for estimating glomerular filtration rate, the evaluation of creatinine reference intervals remains relevant. The present study aimed to establish such reference intervals from a healthy Congolese adult.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis study was based on \u003cem\u003epost-hoc\u003c/em\u003e data of previous epidemiology study conducted in the general population of Kinshasa. Serum Creatinine measurement was performed with enzymatic IDMS-traceable method. The creatinine values being not normally distributed, the median values and interquartile range and the 2.5th and 97.5th percentiles were considered. A value of p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 is the threshold of statistical significance.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOf 2,504 Congolese adults screened, 506 (males, 67.7%) were healthy and were involved in this study. Their mean BSA was 1.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15 m\u003csup\u003e2\u003c/sup\u003e. In males, the median of creatinine was 0.96 [0.87;1.05] mg/dl and percentiles 2.5th and 97.5th were 0.65 and 1.22 mg/dL, respectively. The reference intervals were between 0.65 (95%CI 0.68 to 0.72) and 1.23 (1.20 to 1.24) mg/dL for the lower and the upper limits, respectively. In females, the median of creatinine was 0.72 [0.66;0.80] mg/dl and percentiles 2.5th and 97.5th were 0.50 and 0.95 mg/dL, respectively. The reference intervals were between 0.52 (95%CI 0.50 to 0.54) and 0.95 (0.91 to 0.96) mg/dL for the lower and the upper limits respectively.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe reference intervals for Congolese adults seem close to these of White Europeans, with slightly higher values in Congolese compared to Caucasians, but lower than those of the African-Americans.\u003c/p\u003e","manuscriptTitle":"Reference intervals for serum creatinine for healthy adults in central Africa: a post-hoc analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-13 08:55:43","doi":"10.21203/rs.3.rs-6198894/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-06-11T06:24:16+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-09T22:11:24+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-03T21:04:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"78085868714561647158373125029308615030","date":"2025-06-01T08:51:34+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-29T20:27:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"242475846026003545181372980096706578291","date":"2025-05-20T16:54:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"71488468732996824553076038315443300143","date":"2025-05-10T13:05:06+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-05-08T12:33:42+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-05-07T11:11:42+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-06T10:28:58+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-06T10:26:50+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Nephrology","date":"2025-03-10T23:35:03+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-nephrology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bnep","sideBox":"Learn more about [BMC Nephrology](http://bmcnephrol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bnep/default.aspx","title":"BMC Nephrology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"00042ab3-5724-4828-8a05-fa6104dea0c4","owner":[],"postedDate":"May 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-11-03T15:59:36+00:00","versionOfRecord":{"articleIdentity":"rs-6198894","link":"https://doi.org/10.1186/s12882-025-04538-w","journal":{"identity":"bmc-nephrology","isVorOnly":false,"title":"BMC Nephrology"},"publishedOn":"2025-10-30 15:57:03","publishedOnDateReadable":"October 30th, 2025"},"versionCreatedAt":"2025-05-13 08:55:43","video":"","vorDoi":"10.1186/s12882-025-04538-w","vorDoiUrl":"https://doi.org/10.1186/s12882-025-04538-w","workflowStages":[]},"version":"v1","identity":"rs-6198894","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6198894","identity":"rs-6198894","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}