Early Hemoglobin Trajectories as Predictors of Initial Graft Function in Kidney Transplant Recipients

Early Hemoglobin Trajectories as Predictors of Initial Graft Function in Kidney Transplant Recipients | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Early Hemoglobin Trajectories as Predictors of Initial Graft Function in Kidney Transplant Recipients Abdolamir Atapour, Faeze Haghshenas This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7960560/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract Background Early detection of suboptimal kidney allograft recovery is clinically important, yet conventional markers such as creatinine often lag. Prior studies mostly assessed post-transplant anemia at later time points and did not examine daily hemoglobin (Hb) dynamics during the first postoperative week. Methods We retrospectively analyzed 859 adult kidney transplant recipients (Khorshid Hospital, Iran, 2011–2025). Exclusions included abnormal iron status, parathyroid disorders, active bleeding, baseline rejection, post-transplant dialysis, or erythropoietin/transfusion. Daily Hb, serum creatinine (Cr), and estimated glomerular filtration rate(eGFR) (CKD‑EPI 2021, race‑free) were recorded for post-operative day (POD)1–7. Hb slope (g/dL/day) was calculated via linear regression, and patients were classified as Hb Risers (slope > 0) or Non-Risers. Primary endpoint was eGFR at POD7. Analyses included repeated-measures, Pearson correlations, multivariable regression (adjusted for age, sex, baseline Cr, immunosuppressants), and mixed-effects models for Cr trajectories. Results Mean Hb declined until POD3 and recovered by POD6–7; Cr fell and eGFR rose correspondingly. Hb Risers (57.9%) had faster Cr recovery and higher eGFR at POD7. In adjusted regression, Hb slope independently predicted eGFR_day7 (+ 23.1 mL/min/1.73 m² per 1 g/dL/day; 95% CI 17.0–29.2; p < 0.001). Mixed-effects models confirmed faster renal recovery in Risers. Conclusions Early, daily Hb trajectories during the first postoperative week closely parallel renal recovery. Hb slope provides complementary, independent information beyond baseline creatinine, highlighting its potential as a practical early indicator of graft function. Prospective multicenter validation and mechanistic studies are warranted. kidney transplantation hemoglobin early graft function surrogate marker anemia Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Background Kidney transplantation is the preferred therapy for end‑stage renal disease( 1 ), yet complications such as anemia are common and multifactorial( 2 ). Post‑transplant anemia may reflect suboptimal erythropoietin production by the graft, inflammation, immunosuppressive therapy, or perioperative factors, and could therefore provide early signals of impaired graft recovery. Conventional laboratory markers (serum creatinine, urea) may lag behind true physiologic recovery( 3 ). While tubular injury biomarkers (e.g., NGAL) rise early, their availability is limited in many settings( 4 ). Hemoglobin is universally measured and integrates aspects of erythropoiesis and volume status; tracking its early postoperative trajectory may therefore offer a practical adjunct for early graft monitoring. We investigated whether Hb trajectories during the first postoperative week are associated with early graft function as measured by creatinine and eGFR, and whether Hb slope independently predicts eGFR at hospital day 7. Methods Study design and participants . Retrospective cohort of adult (≥ 18 years) kidney transplant recipients at Khorshid Hospital, Isfahan, Iran (March 2011–March 2025). Exclusion criteria removed conditions that directly affect Hb dynamics (abnormal iron status requiring supplementation, parathyroid disorders, active bleeding, baseline biopsy‑proven rejection, need for dialysis after transplantation, exogenous erythropoietin or packed RBC transfusion). The first postoperative week was selected to capture early Hb and graft function changes during the standard inpatient stay, avoiding bias from patients with prolonged hospitalization due to complications. Data extraction . Demographics, daily laboratory results (Hb, serum Cr) and select interventions were abstracted from electronic records. Laboratory values from POD1 to POD7 were the primary focus; implausible values (Hb 20 g/dL, Cr 15 mg/dL) were excluded. Estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI 2021 race-free Eq. (5), which provides improved accuracy across a wide range of kidney functions compared to MDRD and is currently guideline-recommended( 6 ). Exposure definition . For each patient, an Hb slope (g/dL/day) was estimated by ordinary least squares regression across available Hb measurements on POD1–7 (minimum two measurements required). Patients were categorized as Hb Risers (slope > 0) or Non‑risers (slope ≤ 0). Sensitivity analyses considered Hb slope as a continuous predictor and categorized into tertiles. Endpoints . Primary endpoint: eGFR on POD7. Secondary endpoints: daily Cr trajectories POD1–7, eGFR trajectories POD1–7, and correlation metrics between Hb and renal markers. Statistical analysis . Continuous variables are presented as mean ± SD and categorical variables as counts (percent). Group comparisons used independent t‑tests or χ² tests as appropriate. Longitudinal analyses were performed using repeated‑measures methods and linear mixed‑effects models with random intercepts for patient to account for within‑patient correlation. The primary multivariable analysis used linear regression to predict eGFR_day7 with Hb_slope as the primary predictor, adjusted for age, sex, baseline CrD1, and key immunosuppressive agents when recorded; heteroskedasticity‑robust standard errors were used. Missing data were described, and complete‑case analyses were supplemented with sensitivity analyses (e.g., multiple imputation) when missingness suggested possible bias. Statistical significance was set at two‑sided p < 0.05. Analyses were performed using Python (pandas, statsmodels, matplotlib). Results Cohort characteristics and data completeness. 859 patients met inclusion criteria. Mean age was 44.4 ± 14.0 years and 66.8% were male. Median length of stay was 9 days [IQR 7–13]. Hb slopes could be computed for the majority; overall missingness for key model variables was low (Hb_slope missing 2.2%; CrD1 missing 2.9%; eGFR_day7 missing 1.7%). Complete‑case analysis for the adjusted regression included n = 830 patients( Table 1 ). Table 1 Baseline Characteristics variable value N 859 Age (years), mean ± SD 44.4 ± 14.0 Male/Female (n) 574/285 Length of stay, median [IQR] 9 [7–13] Day 1 Hb, mean ± SD (g/dL) 9.03 ± 1.93 Day 1 Cr, mean ± SD (mg/dL) 3.18 ± 1.78 Hemoglobin and renal trajectories . Mean Hb declined modestly until POD3 (8.57 ± 1.82 g/dL) then rose to 8.93 ± 1.86 g/dL by POD6–7. Serum creatinine fell from 3.18 ± 1.78 mg/dL on POD1 to 2.12 ± 1.70 mg/dL on POD3 and stabilized thereafter; mean eGFR rose from 30.9 ± 19.5 mL/min/1.73 m² (POD1) to 60.6 ± 29.4 mL/min/1.73 m² (POD7)(Table 2 ). Pearson correlations between pooled daily Hb and Cr (r=–0.093, p < 0.001) and Hb and eGFR (r = + 0.118, p < 0.001) were statistically significant but small in magnitude(Fig. 1 , 2 ). Table 2 Daily laboratory values(Days1-7) Day n_Hb Hb mean ± SD (g/dL) n_Cr Cr mean ± SD (mg/dL) n_eGFR eGFR mean ± SD 1 832 9.03 ± 1.93 833 3.18 ± 1.78 833 30.9 ± 19.5 2 832 8.80 ± 1.90 834 2.43 ± 1.77 834 47.4 ± 28.4 3 800 8.57 ± 1.82 811 2.12 ± 1.70 811 55.8 ± 30.6 4 794 8.61 ± 1.84 805 1.94 ± 1.65 805 60.9 ± 30.9 5 791 8.81 ± 1.85 799 1.85 ± 1.63 799 63.5 ± 30.3 6 772 8.97 ± 1.87 779 1.80 ± 1.65 779 64.7 ± 29.6 7 610 8.93 ± 1.86 614 1.91 ± 1.63 614 60.6 ± 29.4 Hb Risers vs Non‑risers . Based on Hb slope, 497 patients (57.9%) were Hb Risers. In unadjusted comparisons, Risers had lower Cr at baseline (POD1 Cr 2.84 vs 3.37 mg/dL) and lower Cr throughout POD1–7 (POD7 Cr 1.38 vs 2.35 mg/dL)(Table 3 ). Mean eGFR at last inpatient day was higher in Risers (74.8 ± 24.0 vs 57.3 ± 28.5 mL/min/1.73 m²; mean difference + 17.5 mL/min/1.73 m², p < 0.001)(Fig. 3 ). Table 3 Cr in Riser Group VS non Riser creatinine(mg/dL) Non riser riser Day1 3.37 2.84 Day2 2.66 1.95 Day3 2.38 1.61 Day4 2.20 1.45 Day5 2.09 1.41 Day6 2.02 1.40 Day7 2.35 1.38 Adjusted association of Hb slope with eGFR_day7 . In a multivariable linear regression (complete‑case n = 830) adjusting for age, sex, and CrD1 (and including recorded immunosuppressant indicators), Hb_slope was independently associated with eGFR_day7: β = +23.10 mL/min/1.73 m² per 1 g/dL/day increase in Hb_slope (95% CI 17.02 to 29.18; p < 0.001). Other independent predictors included age (β ≈ −0.42 per year), female sex (β ≈ −11.16), and baseline creatinine CrD1 (β ≈ −8.52 per mg/dL)(Fig. 4 ). The model R² was 0.404, indicating that the model explained ~ 40% of variability in eGFR_day7. Sensitivity analyses . Categorizing Hb_slope into tertiles revealed a stepwise relationship: higher tertiles were associated with progressively higher eGFR_day7 even after adjustment (trend p < 0.001). Linear mixed‑effects modeling of daily Cr (random intercepts) confirmed that HbRiser status was associated with lower overall creatinine (fixed effect for Hb riser ≈ − 1.18 mg/dL, p < 0.001) and that creatinine decreased over time (fixed effect for day ≈ − 0.241 mg/dL/day, p < 0.001), consistent with more favorable early recovery in Risers(Fig. 5 ). Multiple imputation for missing covariates was not required because missingness in key variables was < 10% and the main results were robust in sensitivity checks. Supplementary laboratory markers. Platelet counts dipped by POD3 and rebounded by POD7. Liver enzymes showed modest, variable changes(Table 4 ). These did not explain the primary Hb–renal associations. Table 4 Supplementary Data(Day1-7) Day n_AST AST mean ± SD(U/L) n_ALT ALT mean ± SD(U/L) n_ALP ALP mean ± SD(U/L) n_plt Plt mean ± SD(×10³/µL) 1 229 29.25 ± 56.48 229 20.11 ± 36.58 224 262.33 ± 237.11 838 153.11 ± 52.31 2 153 32.29 ± 61.02 153 20.35 ± 35.58 152 248.19 ± 194.46 836 149.19 ± 52.86 3 238 29.62 ± 61.33 237 17.26 ± 40.80 237 217.04 ± 131.27 811 143.13 ± 53.70 4 192 32.24 ± 38.06 191 32.10 ± 48.12 189 217.43 ± 135.00 803 146.72 ± 56.87 5 290 29.99 ± 47.22 290 31.85 ± 46.78 283 229.47 ± 168.42 797 156.51 ± 60.98 6 225 27.54 ± 29.52 225 33.82 ± 47.12 220 261.49 ± 199.62 779 168.06 ± 63.44 7 216 24.15 ± 21.47 216 28.58 ± 45.64 210 224.87 ± 118.89 613 178.22 ± 66.39 Discussion In this large, single‑center cohort, we observed that early Hb trajectories parallel renal recovery. Hb slope during POD1–7 was independently associated with eGFR at one week after transplantation, even after adjustment for age, sex and baseline creatinine. The association was robust across multiple analytic approaches (continuous slope, tertiles, and longitudinal mixed models). Compared with previous research that primarily focused on anemia prevalence at later post-transplant time points( 2 ), our study offers a unique insight into the early, daily dynamics of hemoglobin and renal function. Interpretation . Rising Hb in the first postoperative week likely reflects a combination of restored renal erythropoietin production, improved hemodynamics, and stabilization of volume status that accompany graft recovery. Because Hb is routinely measured, its early trajectory can serve as a low‑cost, widely available adjunctive signal to help triage patients for closer surveillance or earlier diagnostic evaluation when recovery appears delayed. Strengths and limitations . Strengths include a large sample size and daily inpatient laboratory measurements enabling trajectory analyses. Limitations include the retrospective, single‑center design, potential residual confounding (e.g., donor type, ischemia time, perioperative blood loss), and limited follow‑up beyond hospitalization. Conclusion In conclusion, early post-transplant hemoglobin trends closely mirror renal recovery and may serve as a practical, easily measurable surrogate marker of early graft function. Monitoring daily Hb may provide clinicians with a simple tool to identify patients at risk of delayed graft recovery and guide timely interventions in the immediate postoperative period. Future studies with multicenter designs, longer follow-up, and advanced modeling approaches (e.g., random-slope mixed models or machine learning) are warranted to validate and generalize these findings. Declarations Ethical approval: This study was conducted in accordance with the principles of the Declaration of Helsinki. The study protocol was reviewed and approved by the Ethics Committee of Isfahan University of Medical Sciences (Approval ID: IR.MUI.MED.REC.1402.221). Given the retrospective design and use of anonymized data, the requirement for informed consent was waived by the ethics committee. Consent for publication: Not applicable Availability of data and materials: The datasets analyzed during the current study are not publicly available due to patient privacy, institutional policies, and ethical restrictions of Isfahan University of Medical Sciences. However, de-identified data may be made available from the corresponding author upon reasonable request and with permission from the institutional ethics committee. Competing Interest : The authors declare no conflicts of interest related to this study. Funding: Financial support was provided by the Vice Chancellor for Research (Grant No. 59375). Authors' contribution: AA contributed to the conception of the study and the interpretation of the results. FH was responsible for data collection, data analysis, and drafting the manuscript. Both authors read and approved the final manuscript. Acknowledgments: We sincerely thank the staff of the Kidney Transplant Unit and Medical Records Department at Khorshid Hospital, Isfahan, Iran, for their support in data collection. We also appreciate the patients who contributed to this study. References Tonelli M, Wiebe N, Knoll G, Bello A, Browne S, Jadhav D, et al. Systematic review: kidney transplantation compared with dialysis in clinically relevant outcomes. Am J Transpl Off J Am Soc Transpl Am Soc Transpl Surg. 2011;11(10):2093–109. Schechter A, Gafter-Gvili A, Shepshelovich D, Rahamimov R, Gafter U, Mor E, et al. Post renal transplant anemia: severity, causes and their association with graft and patient survival. BMC Nephrol. 2019;20(1):51. Lazarou C, Moysidou E, Christodoulou M, Lioulios G, Sampani E, Dimitriadis C, et al. Non-Invasive Biomarkers for Early Diagnosis of Kidney Allograft Dysfunction: Current and Future Applications in the Era of Precision Medicine. Med Kaunas Lith. 2025;61(2):262. Antonucci E, Lippi G, Ticinesi A, Pigna F, Guida L, Morelli I, et al. Neutrophil gelatinase-associated lipocalin (NGAL): a promising biomarker for the early diagnosis of acute kidney injury (AKI). Acta Bio-Medica Atenei Parm. 2014;85(3):289–94. Inker LA, Eneanya ND, Coresh J, Tighiouart H, Wang D, Sang Y, et al. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385(19):1737–49. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–314. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 07 Dec, 2025 Reviewers agreed at journal 27 Nov, 2025 Reviewers agreed at journal 25 Nov, 2025 Reviewers invited by journal 25 Nov, 2025 Editor invited by journal 29 Oct, 2025 Editor assigned by journal 29 Oct, 2025 Submission checks completed at journal 29 Oct, 2025 First submitted to journal 27 Oct, 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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1","display":"","copyAsset":false,"role":"figure","size":328814,"visible":true,"origin":"","legend":"\u003cp\u003eHemoglobin vs Creatinine scatter with fitted line\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7960560/v1/a555d8ad290c52a9bcd2fb25.png"},{"id":97142525,"identity":"dec70170-4832-4cbd-8fe7-15422e4022e6","added_by":"auto","created_at":"2025-12-01 10:07:41","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":556758,"visible":true,"origin":"","legend":"\u003cp\u003eHemoglobin vs eGFR scatter with fitted line\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7960560/v1/a3aa5de94b9b8585e5c2cbb8.png"},{"id":97128551,"identity":"99b0d3c7-b7ac-4fe7-8261-c2fd08d7e9fe","added_by":"auto","created_at":"2025-12-01 08:35:17","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":37034,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of final eGFR between Hb Risers and Non-Risers\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7960560/v1/8a59a465e93ebc1bc64de2dd.jpeg"},{"id":97128554,"identity":"046dca34-f5b2-4a10-99b2-582624615d52","added_by":"auto","created_at":"2025-12-01 08:35:17","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":47074,"visible":true,"origin":"","legend":"\u003cp\u003eMultivariable Regression\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7960560/v1/591c7e68d254ef999a31b377.jpeg"},{"id":97128567,"identity":"74312536-a200-4cd9-9cb5-dcecad334088","added_by":"auto","created_at":"2025-12-01 08:35:17","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":52561,"visible":true,"origin":"","legend":"\u003cp\u003eMean Creatinine Trajectory by Group\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7960560/v1/f8cdc1c068fd674f0c32500d.jpeg"},{"id":97145298,"identity":"6c65c730-4c8e-4ec6-9f4a-533bb61b7ec6","added_by":"auto","created_at":"2025-12-01 10:13:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1285204,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7960560/v1/bb8811f0-cf1c-4eb3-9f54-00a1f482c849.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Early Hemoglobin Trajectories as Predictors of Initial Graft Function in Kidney Transplant Recipients","fulltext":[{"header":"Background","content":"\u003cp\u003eKidney transplantation is the preferred therapy for end‑stage renal disease(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e), yet complications such as anemia are common and multifactorial(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Post‑transplant anemia may reflect suboptimal erythropoietin production by the graft, inflammation, immunosuppressive therapy, or perioperative factors, and could therefore provide early signals of impaired graft recovery. Conventional laboratory markers (serum creatinine, urea) may lag behind true physiologic recovery(\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). While tubular injury biomarkers (e.g., NGAL) rise early, their availability is limited in many settings(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Hemoglobin is universally measured and integrates aspects of erythropoiesis and volume status; tracking its early postoperative trajectory may therefore offer a practical adjunct for early graft monitoring. We investigated whether Hb trajectories during the first postoperative week are associated with early graft function as measured by creatinine and eGFR, and whether Hb slope independently predicts eGFR at hospital day 7.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cem\u003eStudy design and participants\u003c/em\u003e. Retrospective cohort of adult (\u0026ge;\u0026thinsp;18 years) kidney transplant recipients at Khorshid Hospital, Isfahan, Iran (March 2011\u0026ndash;March 2025). Exclusion criteria removed conditions that directly affect Hb dynamics (abnormal iron status requiring supplementation, parathyroid disorders, active bleeding, baseline biopsy‑proven rejection, need for dialysis after transplantation, exogenous erythropoietin or packed RBC transfusion). The first postoperative week was selected to capture early Hb and graft function changes during the standard inpatient stay, avoiding bias from patients with prolonged hospitalization due to complications.\u003c/p\u003e\u003cp\u003e\u003cem\u003eData extraction\u003c/em\u003e. Demographics, daily laboratory results (Hb, serum Cr) and select interventions were abstracted from electronic records. Laboratory values from POD1 to POD7 were the primary focus; implausible values (Hb\u0026thinsp;\u0026lt;\u0026thinsp;5 or \u0026gt;\u0026thinsp;20 g/dL, Cr\u0026thinsp;\u0026lt;\u0026thinsp;0.2 or \u0026gt;\u0026thinsp;15 mg/dL) were excluded. Estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI 2021 race-free Eq.\u0026nbsp;(5), which provides improved accuracy across a wide range of kidney functions compared to MDRD and is currently guideline-recommended(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cem\u003eExposure definition\u003c/em\u003e. For each patient, an Hb slope (g/dL/day) was estimated by ordinary least squares regression across available Hb measurements on POD1\u0026ndash;7 (minimum two measurements required). Patients were categorized as Hb Risers (slope\u0026thinsp;\u0026gt;\u0026thinsp;0) or Non‑risers (slope\u0026thinsp;\u0026le;\u0026thinsp;0). Sensitivity analyses considered Hb slope as a continuous predictor and categorized into tertiles.\u003c/p\u003e\u003cp\u003e\u003cem\u003eEndpoints\u003c/em\u003e. Primary endpoint: eGFR on POD7. Secondary endpoints: daily Cr trajectories POD1\u0026ndash;7, eGFR trajectories POD1\u0026ndash;7, and correlation metrics between Hb and renal markers.\u003c/p\u003e\u003cp\u003e\u003cem\u003eStatistical analysis\u003c/em\u003e. Continuous variables are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD and categorical variables as counts (percent). Group comparisons used independent t‑tests or χ\u0026sup2; tests as appropriate. Longitudinal analyses were performed using repeated‑measures methods and linear mixed‑effects models with random intercepts for patient to account for within‑patient correlation. The primary multivariable analysis used linear regression to predict eGFR_day7 with Hb_slope as the primary predictor, adjusted for age, sex, baseline CrD1, and key immunosuppressive agents when recorded; heteroskedasticity‑robust standard errors were used. Missing data were described, and complete‑case analyses were supplemented with sensitivity analyses (e.g., multiple imputation) when missingness suggested possible bias. Statistical significance was set at two‑sided p\u0026thinsp;\u0026lt;\u0026thinsp;0.05. Analyses were performed using Python (pandas, statsmodels, matplotlib).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cem\u003eCohort characteristics and data completeness. 859 patients met inclusion criteria. Mean age was 44.4\u0026thinsp;\u0026plusmn;\u0026thinsp;14.0 years and 66.8% were male. Median length of stay was 9 days [IQR 7\u0026ndash;13]. Hb slopes could be computed for the majority; overall missingness for key model variables was low (Hb_slope missing 2.2%; CrD1 missing 2.9%; eGFR_day7 missing 1.7%). Complete‑case analysis for the adjusted regression included n\u0026thinsp;=\u0026thinsp;830 patients(\u003c/em\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cem\u003e).\u003c/em\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\u003eBaseline Characteristics\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003evariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003evalue\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e859\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (years), mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e44.4\u0026thinsp;\u0026plusmn;\u0026thinsp;14.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMale/Female (n)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e574/285\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLength of stay, median [IQR]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9 [7\u0026ndash;13]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay 1 Hb, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD (g/dL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.93\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay 1 Cr, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD (mg/dL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.18\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003eHemoglobin and renal trajectories\u003c/em\u003e. Mean Hb declined modestly until POD3 (8.57\u0026thinsp;\u0026plusmn;\u0026thinsp;1.82 g/dL) then rose to 8.93\u0026thinsp;\u0026plusmn;\u0026thinsp;1.86 g/dL by POD6\u0026ndash;7. Serum creatinine fell from 3.18\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78 mg/dL on POD1 to 2.12\u0026thinsp;\u0026plusmn;\u0026thinsp;1.70 mg/dL on POD3 and stabilized thereafter; mean eGFR rose from 30.9\u0026thinsp;\u0026plusmn;\u0026thinsp;19.5 mL/min/1.73 m\u0026sup2; (POD1) to 60.6\u0026thinsp;\u0026plusmn;\u0026thinsp;29.4 mL/min/1.73 m\u0026sup2; (POD7)(Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Pearson correlations between pooled daily Hb and Cr (r=\u0026ndash;0.093, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and Hb and eGFR (r\u0026thinsp;=\u0026thinsp;+\u0026thinsp;0.118, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) were statistically significant but small in magnitude(Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e,\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\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\u003eDaily laboratory values(Days1-7)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\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=\"\u0026plusmn;\" 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=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003en_Hb\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHb mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD (g/dL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003en_Cr\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCr mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD (mg/dL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003en_eGFR\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eeGFR mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e832\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e9.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e833\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e3.18\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e833\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e30.9\u0026thinsp;\u0026plusmn;\u0026thinsp;19.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e832\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.80\u0026thinsp;\u0026plusmn;\u0026thinsp;1.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e834\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e2.43\u0026thinsp;\u0026plusmn;\u0026thinsp;1.77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e834\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e47.4\u0026thinsp;\u0026plusmn;\u0026thinsp;28.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.57\u0026thinsp;\u0026plusmn;\u0026thinsp;1.82\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e811\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e2.12\u0026thinsp;\u0026plusmn;\u0026thinsp;1.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e811\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e55.8\u0026thinsp;\u0026plusmn;\u0026thinsp;30.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e794\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.61\u0026thinsp;\u0026plusmn;\u0026thinsp;1.84\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e805\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e1.94\u0026thinsp;\u0026plusmn;\u0026thinsp;1.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e805\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e60.9\u0026thinsp;\u0026plusmn;\u0026thinsp;30.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e791\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.81\u0026thinsp;\u0026plusmn;\u0026thinsp;1.85\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e799\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e1.85\u0026thinsp;\u0026plusmn;\u0026thinsp;1.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e799\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e63.5\u0026thinsp;\u0026plusmn;\u0026thinsp;30.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e772\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.97\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e779\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e1.80\u0026thinsp;\u0026plusmn;\u0026thinsp;1.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e779\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e64.7\u0026thinsp;\u0026plusmn;\u0026thinsp;29.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e610\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.93\u0026thinsp;\u0026plusmn;\u0026thinsp;1.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e614\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e1.91\u0026thinsp;\u0026plusmn;\u0026thinsp;1.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e614\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e60.6\u0026thinsp;\u0026plusmn;\u0026thinsp;29.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003eHb Risers vs Non‑risers\u003c/em\u003e. Based on Hb slope, 497 patients (57.9%) were Hb Risers. In unadjusted comparisons, Risers had lower Cr at baseline (POD1 Cr 2.84 vs 3.37 mg/dL) and lower Cr throughout POD1\u0026ndash;7 (POD7 Cr 1.38 vs 2.35 mg/dL)(Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Mean eGFR at last inpatient day was higher in Risers (74.8\u0026thinsp;\u0026plusmn;\u0026thinsp;24.0 vs 57.3\u0026thinsp;\u0026plusmn;\u0026thinsp;28.5 mL/min/1.73 m\u0026sup2;; mean difference\u0026thinsp;+\u0026thinsp;17.5 mL/min/1.73 m\u0026sup2;, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001)(Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCr in Riser Group VS non Riser\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ecreatinine(mg/dL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNon riser\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eriser\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e3.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2.84\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.95\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.61\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.45\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.41\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.40\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.38\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003eAdjusted association of Hb slope with eGFR_day7\u003c/em\u003e. In a multivariable linear regression (complete‑case n\u0026thinsp;=\u0026thinsp;830) adjusting for age, sex, and CrD1 (and including recorded immunosuppressant indicators), Hb_slope was independently associated with eGFR_day7: β = +23.10 mL/min/1.73 m\u0026sup2; per 1 g/dL/day increase in Hb_slope (95% CI 17.02 to 29.18; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Other independent predictors included age (β \u0026asymp; \u0026minus;0.42 per year), female sex (β \u0026asymp; \u0026minus;11.16), and baseline creatinine CrD1 (β \u0026asymp; \u0026minus;8.52 per mg/dL)(Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The model R\u0026sup2; was 0.404, indicating that the model explained\u0026thinsp;~\u0026thinsp;40% of variability in eGFR_day7.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003eSensitivity analyses\u003c/em\u003e. Categorizing Hb_slope into tertiles revealed a stepwise relationship: higher tertiles were associated with progressively higher eGFR_day7 even after adjustment (trend p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Linear mixed‑effects modeling of daily Cr (random intercepts) confirmed that HbRiser status was associated with lower overall creatinine (fixed effect for Hb riser\u0026thinsp;\u0026asymp;\u0026thinsp;\u0026minus;\u0026thinsp;1.18 mg/dL, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and that creatinine decreased over time (fixed effect for day\u0026thinsp;\u0026asymp;\u0026thinsp;\u0026minus;\u0026thinsp;0.241 mg/dL/day, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), consistent with more favorable early recovery in Risers(Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Multiple imputation for missing covariates was not required because missingness in key variables was \u0026lt;\u0026thinsp;10% and the main results were robust in sensitivity checks.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003eSupplementary laboratory markers.\u003c/em\u003e Platelet counts dipped by POD3 and rebounded by POD7. Liver enzymes showed modest, variable changes(Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). These did not explain the primary Hb\u0026ndash;renal associations.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSupplementary Data(Day1-7)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\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=\"\u0026plusmn;\" 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=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDay\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003en_AST\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAST mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(U/L)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003en_ALT\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eALT mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(U/L)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003en_ALP\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eALP mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(U/L)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003en_plt\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003ePlt mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(\u0026times;10\u0026sup3;/\u0026micro;L)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e229\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e29.25\u0026thinsp;\u0026plusmn;\u0026thinsp;56.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e229\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e20.11\u0026thinsp;\u0026plusmn;\u0026thinsp;36.58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e224\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e262.33\u0026thinsp;\u0026plusmn;\u0026thinsp;237.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e838\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e153.11\u0026thinsp;\u0026plusmn;\u0026thinsp;52.31\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e153\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e32.29\u0026thinsp;\u0026plusmn;\u0026thinsp;61.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e153\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e20.35\u0026thinsp;\u0026plusmn;\u0026thinsp;35.58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e152\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e248.19\u0026thinsp;\u0026plusmn;\u0026thinsp;194.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e836\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e149.19\u0026thinsp;\u0026plusmn;\u0026thinsp;52.86\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e238\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e29.62\u0026thinsp;\u0026plusmn;\u0026thinsp;61.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e237\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e17.26\u0026thinsp;\u0026plusmn;\u0026thinsp;40.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e237\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e217.04\u0026thinsp;\u0026plusmn;\u0026thinsp;131.27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e811\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e143.13\u0026thinsp;\u0026plusmn;\u0026thinsp;53.70\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e192\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e32.24\u0026thinsp;\u0026plusmn;\u0026thinsp;38.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e191\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e32.10\u0026thinsp;\u0026plusmn;\u0026thinsp;48.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e189\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e217.43\u0026thinsp;\u0026plusmn;\u0026thinsp;135.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e803\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e146.72\u0026thinsp;\u0026plusmn;\u0026thinsp;56.87\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e290\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e29.99\u0026thinsp;\u0026plusmn;\u0026thinsp;47.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e290\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e31.85\u0026thinsp;\u0026plusmn;\u0026thinsp;46.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e283\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e229.47\u0026thinsp;\u0026plusmn;\u0026thinsp;168.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e797\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e156.51\u0026thinsp;\u0026plusmn;\u0026thinsp;60.98\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e225\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e27.54\u0026thinsp;\u0026plusmn;\u0026thinsp;29.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e225\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e33.82\u0026thinsp;\u0026plusmn;\u0026thinsp;47.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e220\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e261.49\u0026thinsp;\u0026plusmn;\u0026thinsp;199.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e779\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e168.06\u0026thinsp;\u0026plusmn;\u0026thinsp;63.44\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e216\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e24.15\u0026thinsp;\u0026plusmn;\u0026thinsp;21.47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e216\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e28.58\u0026thinsp;\u0026plusmn;\u0026thinsp;45.64\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e210\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e224.87\u0026thinsp;\u0026plusmn;\u0026thinsp;118.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e613\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e178.22\u0026thinsp;\u0026plusmn;\u0026thinsp;66.39\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this large, single‑center cohort, we observed that early Hb trajectories parallel renal recovery. Hb slope during POD1\u0026ndash;7 was independently associated with eGFR at one week after transplantation, even after adjustment for age, sex and baseline creatinine. The association was robust across multiple analytic approaches (continuous slope, tertiles, and longitudinal mixed models). Compared with previous research that primarily focused on anemia prevalence at later post-transplant time points(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e), our study offers a unique insight into the early, daily dynamics of hemoglobin and renal function.\u003c/p\u003e\u003cp\u003e\u003cem\u003eInterpretation\u003c/em\u003e. Rising Hb in the first postoperative week likely reflects a combination of restored renal erythropoietin production, improved hemodynamics, and stabilization of volume status that accompany graft recovery. Because Hb is routinely measured, its early trajectory can serve as a low‑cost, widely available adjunctive signal to help triage patients for closer surveillance or earlier diagnostic evaluation when recovery appears delayed.\u003c/p\u003e\u003cp\u003e\u003cem\u003eStrengths and limitations\u003c/em\u003e. Strengths include a large sample size and daily inpatient laboratory measurements enabling trajectory analyses. Limitations include the retrospective, single‑center design, potential residual confounding (e.g., donor type, ischemia time, perioperative blood loss), and limited follow‑up beyond hospitalization.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, early post-transplant hemoglobin trends closely mirror renal recovery and may serve as a practical, easily measurable surrogate marker of early graft function. Monitoring daily Hb may provide clinicians with a simple tool to identify patients at risk of delayed graft recovery and guide timely interventions in the immediate postoperative period. Future studies with multicenter designs, longer follow-up, and advanced modeling approaches (e.g., random-slope mixed models or machine learning) are warranted to validate and generalize these findings.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eEthical approval: This study was conducted in accordance with the principles of the Declaration of Helsinki. The study protocol was reviewed and approved by the Ethics Committee of Isfahan University of Medical Sciences (Approval ID: IR.MUI.MED.REC.1402.221). Given the retrospective design and use of anonymized data, the requirement for informed consent was waived by the ethics committee.\u003c/p\u003e\n\u003cp\u003eConsent for publication: Not applicable\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials: The datasets analyzed during the current study are not publicly available due to patient privacy, institutional policies, and ethical restrictions of Isfahan University of Medical Sciences. However, de-identified data may be made available from the corresponding author upon reasonable request and with permission from the institutional ethics committee.\u003c/p\u003e\n\u003cp\u003eCompeting Interest\u003cstrong\u003e:\u0026nbsp;\u003c/strong\u003eThe authors declare no conflicts of interest related to this study.\u003c/p\u003e\n\u003cp\u003eFunding: Financial support was provided by the Vice Chancellor for Research (Grant No. 59375).\u003c/p\u003e\n\u003cp\u003eAuthors\u0026apos; contribution: AA contributed to the conception of the study and the interpretation of the results. FH was responsible for data collection, data analysis, and drafting the manuscript. Both authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003eAcknowledgments:\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eWe sincerely thank the staff of the Kidney Transplant Unit and Medical Records Department at Khorshid Hospital, Isfahan, Iran, for their support in data collection. We also appreciate the patients who contributed to this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eTonelli M, Wiebe N, Knoll G, Bello A, Browne S, Jadhav D, et al. Systematic review: kidney transplantation compared with dialysis in clinically relevant outcomes. Am J Transpl Off J Am Soc Transpl Am Soc Transpl Surg. 2011;11(10):2093\u0026ndash;109.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSchechter A, Gafter-Gvili A, Shepshelovich D, Rahamimov R, Gafter U, Mor E, et al. Post renal transplant anemia: severity, causes and their association with graft and patient survival. BMC Nephrol. 2019;20(1):51.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLazarou C, Moysidou E, Christodoulou M, Lioulios G, Sampani E, Dimitriadis C, et al. Non-Invasive Biomarkers for Early Diagnosis of Kidney Allograft Dysfunction: Current and Future Applications in the Era of Precision Medicine. Med Kaunas Lith. 2025;61(2):262.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAntonucci E, Lippi G, Ticinesi A, Pigna F, Guida L, Morelli I, et al. Neutrophil gelatinase-associated lipocalin (NGAL): a promising biomarker for the early diagnosis of acute kidney injury (AKI). Acta Bio-Medica Atenei Parm. 2014;85(3):289\u0026ndash;94.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eInker LA, Eneanya ND, Coresh J, Tighiouart H, Wang D, Sang Y, et al. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385(19):1737\u0026ndash;49.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117\u0026ndash;314.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"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":"kidney transplantation, hemoglobin, early graft function, surrogate marker, anemia","lastPublishedDoi":"10.21203/rs.3.rs-7960560/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7960560/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eEarly detection of suboptimal kidney allograft recovery is clinically important, yet conventional markers such as creatinine often lag. Prior studies mostly assessed post-transplant anemia at later time points and did not examine daily hemoglobin (Hb) dynamics during the first postoperative week.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eWe retrospectively analyzed 859 adult kidney transplant recipients (Khorshid Hospital, Iran, 2011\u0026ndash;2025). Exclusions included abnormal iron status, parathyroid disorders, active bleeding, baseline rejection, post-transplant dialysis, or erythropoietin/transfusion. Daily Hb, serum creatinine (Cr), and estimated glomerular filtration rate(eGFR) (CKD‑EPI 2021, race‑free) were recorded for post-operative day (POD)1\u0026ndash;7. Hb slope (g/dL/day) was calculated via linear regression, and patients were classified as Hb Risers (slope\u0026thinsp;\u0026gt;\u0026thinsp;0) or Non-Risers. Primary endpoint was eGFR at POD7. Analyses included repeated-measures, Pearson correlations, multivariable regression (adjusted for age, sex, baseline Cr, immunosuppressants), and mixed-effects models for Cr trajectories.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eMean Hb declined until POD3 and recovered by POD6\u0026ndash;7; Cr fell and eGFR rose correspondingly. Hb Risers (57.9%) had faster Cr recovery and higher eGFR at POD7. In adjusted regression, Hb slope independently predicted eGFR_day7 (+\u0026thinsp;23.1 mL/min/1.73 m\u0026sup2; per 1 g/dL/day; 95% CI 17.0\u0026ndash;29.2; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Mixed-effects models confirmed faster renal recovery in Risers.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eEarly, daily Hb trajectories during the first postoperative week closely parallel renal recovery. Hb slope provides complementary, independent information beyond baseline creatinine, highlighting its potential as a practical early indicator of graft function. Prospective multicenter validation and mechanistic studies are warranted.\u003c/p\u003e","manuscriptTitle":"Early Hemoglobin Trajectories as Predictors of Initial Graft Function in Kidney Transplant Recipients","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-01 08:35:12","doi":"10.21203/rs.3.rs-7960560/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2025-12-08T03:05:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"173732465471598673135699670852294591833","date":"2025-11-27T11:47:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"333690127011314463360926870657257028849","date":"2025-11-25T13:53:56+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-25T10:26:14+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-10-29T16:24:29+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-29T13:12:11+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-29T13:10:42+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Nephrology","date":"2025-10-27T13:06:03+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":"0dbd55f9-87b2-4fd6-86dd-0d5819a3f9f0","owner":[],"postedDate":"December 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-12-01T08:35:12+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-01 08:35:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7960560","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7960560","identity":"rs-7960560","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}