Urinary Retention in Older Adults with Hyponatremia admitted to Acute Medical Wards

Urinary Retention in Older Adults with Hyponatremia admitted to Acute Medical Wards | 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 Urinary Retention in Older Adults with Hyponatremia admitted to Acute Medical Wards Dvorah S. Shapiro, Raphael Ellis, Husam Mouhtaseb, Hiba Abdelkareem, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7228177/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 Hyponatremia and urinary retention are common medical problems. While associations between the two are documented, research has not clearly established the incidence of urinary retention in hyponatremic patients. Objectives To determine the incidence of urinary retention in hyponatremic patients and assess whether urinary catheter insertion affects the sodium correction rate. Methods A prospective, single centre, observational study including patients hospitalized in Internal Medicine and Geriatric wards. A total of 199 older patients (mean age 84.4, 39% men) were investigated: 100 with hyponatremia ≤129 mEq/L (of these, 70 had severe hyponatremia ≤125 mEq/L) and 99 normonatremic controls. The incidence of urinary retention was checked in all groups. Hyponatremic patients underwent complete assessment for the cause of hyponatremia and sodium levels were followed up for 48 hours. Results There was a marked increase in the incidence of urinary retention in older hyponatremic patients compared to those with normal sodium levels (41% vs 21%, p=0.004). The difference was even greater when comparing those with severe hyponatremia to controls (44% vs 21%, p=0.001). Among hyponatremic patients with and without urinary retention, there was no difference in sodium correction rate between the two groups. Patients with polyuria secondary to post-obstructive diuresis had more rapid sodium correction (9.2±6.8 mEq/L vs 5.8±4.8 mEq/L, p=0.05). Conclusions There was a significantly higher incidence of urinary retention in older patients with hyponatremia, which correlates with hyponatremia severity. Post-obstructive diuresis following catheter insertion is associated with more rapid sodium correction. We recommend routine bladder scanning for all patients with hyponatremia. Hyponatremia urinary retention post-obstructive diuresis Key Points Urinary retention occurred in 41% of older hyponatremic patients compared to 21% of normonatremic controls, with the highest incidence (44%) in patients with severe hyponatremia (≤125 mEq/L). Post-obstructive diuresis following urinary catheter insertion was associated with more rapid sodium correction in hyponatremic patients (9.2±6.8 mEq/L vs 5.8±4.8 mEq/L over 48 hours). Routine bladder scanning should be considered for all patients presenting with hyponatremia to identify concurrent urinary retention. Why does this paper matter? This study establishes a clear association between hyponatremia severity and urinary retention in older adults, providing clinicians with evidence to support routine bladder assessment in hyponatremic patients. The findings suggest that identifying and treating urinary retention may influence sodium correction rates, potentially impacting clinical management strategies for this common electrolyte disorder. Introduction Hyponatremia and urinary retention represent significant clinical challenges commonly encountered in acute Medical and Geriatric wards ( 1 , 2 ). The prevalence of hyponatremia is high, affecting approximately one in five older patients ( 3 ), with some studies documenting rates as high as 36–42% among hospitalized patients ( 4 ). Similarly, urinary retention is common, with an estimated incidence of one in eight patients ( 5 ). While several studies have demonstrated an association between these two conditions ( 6 , 7 ), the specific incidence of urinary retention among patients presenting with hyponatremia remains inadequately characterized. One prospective controlled study ( 8 ) examined the reverse association by analysing the incidence of hyponatremia in patients with acute urinary tract obstruction (aUTO). Although the overall incidence of hyponatremia was comparable between patients with aUTO and controls—regardless of age, baseline comorbidities, or cause of admission—important differences emerged upon closer examination. Patients with aUTO demonstrated significantly lower mean sodium levels and a markedly higher incidence of severe hyponatremia compared to controls. Importantly, relief of the urinary obstruction resulted in rapid and significant improvement in serum sodium levels, suggesting a direct pathophysiological relationship between the two conditions. Understanding this bidirectional relationship is crucial for optimizing clinical management and improving patient outcomes in these vulnerable populations. Supporting evidence comes from a case series conducted on a Geriatric ward, which described six older patients presenting with concurrent hyponatremia and urinary retention ( 7 ). In all cases, serum sodium levels normalized and remained stable following foley catheter insertion combined with fluid restriction. Despite extensive diagnostic workups during hospitalization, no alternative etiology for the hyponatremia could be identified beyond the urinary retention itself. Additional anecdotal reports, summarized in two recent studies, have further highlighted the occurrence of hyponatremia in patients with acute urinary tract obstruction, with rapid resolution following relief of the obstruction ( 6 , 8 ). The primary aim of this study was to determine the incidence of urinary retention among patients with hyponatremia by comparing rates between those with severe (< 126 mEq/L) and moderate (126–129 mEq/L) hyponatremia versus patients with normal sodium levels. The secondary aim was to assess whether urinary catheter insertion influenced the rate of sodium correction. Methods This prospective, observational, single-centre study was conducted at Shaare Zedek Medical Centre (SZMC), Jerusalem, Israel, a university-affiliated 1,000-bed general community hospital, between November 2022 and July 2023. During the study period, general medical patients aged 65 years and older with serum sodium levels ≤ 129 mEq/L were enrolled. Patients were excluded if they underwent haemodialysis, had a nephrostomy, ileal conduit, or permanent catheter in situ. The control group comprised older patients (≥ 65 years) admitted to the same medical wards during the study period, who had normal sodium levels (135–145 mEq/L) and were voiding spontaneously without a urinary catheter. All patients underwent a bladder scan. Urinary retention was defined as residual volume > 400 ml ( 9 , 10 ), and patients meeting this criterion had a urinary catheter inserted. Comprehensive demographic and clinical data were collected, including presenting symptoms, medication history (particularly drugs associated with hyponatremia or urinary retention), and physical examination findings. Volemic status was assessed through medical history, physical examination including vital signs, and laboratory investigations. Laboratory workup included complete blood count, biochemistry with serum osmolality, renal function tests, urinary sodium, and urinary osmolality. Thyroid-stimulating hormone (TSH) levels were obtained in most patients, and cortisol levels were measured when adrenal insufficiency was clinically suspected ( 11 ). Most patients underwent chest radiography, with additional imaging studies performed at the discretion of the attending physician. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) was defined clinically as hypotonic hyponatremia with concentrated urine in a euvolemic patient, after excluding adrenal insufficiency and hypothyroidism ( 12 ). Serum sodium levels were repeated within 48 hours of initial measurement. Urine output was monitored following catheter insertion, with post-obstructive diuresis defined as polyuria with urine output exceeding 3 liters per day after catheter insertion ( 13 ). All treatments for hyponatremia were systematically recorded, with concurrent therapies documented separately. Treatment modalities included discontinuation of medications associated with hyponatremia, fluid restriction, intravenous 3% saline, intravenous 0.9% saline for hypovolaemia, and diuretics for hypervolaemia. Statistical Analysis Continuous variables were presented as mean ± standard deviation (SD), while categorical variables were presented as total number and percentage. Categorical variables were compared between study groups using the Chi-square test. For normally distributed continuous variables, t-test or one-way ANOVA were employed. Comparisons of continuous variables with non-normal distribution were performed using the Mann-Whitney U test. The correlation between residual volume and sodium level was calculated using Pearson correlation analysis. A two-tailed p-value of < 0.05 was considered statistically significant. Statistical analyses were performed using Epi-Info software version 7.2 and SPSS version 25. The study was approved by the Ethics Committee of SZMC, (Shaare Zedek Medical Center), approval number 0222-22-SZMC. Written informed consent was not obtained from individual patients, as the study was based on data collected during routine clinical care. Results One hundred and ninety-nine patients were enrolled in the study: 100 patients with hyponatremia < 129 mEq/L (including 70 patients with severe hyponatremia ≤ 125 mEq/L) and 99 normonatremic controls. Patient demographics were well-matched between groups, with no significant differences in age or sex distribution (Table 1 ). Although there was a slightly lower proportion of men in the hyponatremia group (33% vs 45%), this difference was not statistically significant. When comparing sex distribution among patients with urinary retention, the proportions were similar between hyponatremic and control groups (33% vs 38% male, p = 0.83). Table 1 The characteristics of patients according to sodium level Na < 126 mEq/L (n = 70) Na126-129 mEq/L (n = 30) Na < 130 mEq/L (n = 100) Na ≥ 135 mEq/L (n = 99) P value* Age (year), Mean (SD) 84.4 (8.5) 84.9 (7.9) 84.6 (8.3) 84 (8.4) .618 Sex (male) (%) 25 (36) 8 (27) 33 (33) 45(45) .098 Na (mEq/L), M (SD) 119.8 (4.4) 127.1 (1.2) 122 (5.1) 139.1 (2.7) < 0.0005 Urinary retention (%), 31 (44) 10 (33)) 41 (41) 21 (21) .004 Mean volume of retention ml M (SD) 705 (390) 749 (301) 715 (367) 670 (246) 0.63 SD- standard deviation Urinary retention above 400 ml * Between research group (Na < 130) and compare group (Na ≥ 135 mEq/L) We reviewed medications that may cause urinary retention, including anticholinergic drugs, alpha agonists, opioids, and diuretics. The use of these medications did not differ significantly between patients with and without urinary retention across all 199 patients (52% vs 55%, p = 0.61). The incidence of urinary retention was significantly higher in hyponatremic patients compared to those with normal sodium levels (41% vs 21%, p = 0.004). Among the 70 patients with severe hyponatremia, the incidence of urinary retention was even higher at 44% (p = 0.004). Among the 41 hyponatremic patients with urinary retention, the mean retention volume was 715 ± 367 ml, which was comparable to the retention volume in 21 normonatremic patients with urinary retention (670 ± 246 ml, p = 0.61). There was no correlation between retention volume and sodium level (r=-0.063, p = 0.63). Table 2 compares hyponatremic patients with and without urinary retention. These subgroups were similar in age, gender, and comorbidity burden, with no differences in the use of medications commonly causing hyponatremia or medications that may cause urinary retention. Similarly, there was no difference in volume status or laboratory results. Mean baseline sodium levels were comparable between groups (123 mEq/L vs 121 mEq/L, p = 0.178). Of the 41 patients with hyponatremia and urinary retention, 19 (46.3%) had SIADH. Table 2 –Hyponatremic patients with and without urinary retention (above 400 ml) Urinary retention Yes (n = 41) No (n = 59) P value Age(year), M (SD) 84.5 (8.5) 84.7 (8.2) .900 Sex, (male, N (%)) 14 (34) 19 (32) 1.000 Comorbidities, N (%) Diabetes mellitus 13 (32) 18 (31) 1.000 Hypertension 30 (73) 46 (78) .753 Congestive heart failure 11 (27) 19 (32) .723 Cerebrovascular accident 4 ( 10 ) 9 (15) .616 Chronic kidney disease 9 (22) 12 (20) 1.000 Malignancy 4 ( 10 ) 9 (15) .616 Hospitalization reason, N (%) .945 Hyponatremia 8 (20) 14 (24) Fall 5 ( 12 ) 7 ( 12 ) Cardiovascular disease 6 (15) 11 (19) Infection 11 (27) 14 (24) Other 11 (27) 13 (22) Medication, N (%) Thiazide 2 ( 5 ) 4 ( 7 ) 1.000 SSRI 5 ( 12 ) 5 ( 9 ) .786 Opioids 1 ( 2 ) 4 ( 7 ) .608 Medication causing Urinary retention* 17(42) 29(49) .448 Volemic status, N (%) .215 Euvolemic 21 (51) 25 (42) Hypervolemic 12 (29) 13 (22) Hypovolemic 8 (20) 21 (36) Admission Na (mEq/L), Mean (SD) 121 (5.56) 123 (4.95) .178 Admission NA ≤ 125, N(%) 30 (73) 36 (61) .295 NA delta (mEq/L) (48 hours), M (SD) 6.8 (5.4) 6.1 (5.4) .518 Post Micturition Volume (ml), M (SD) 715(367) 151(116) < 0.005 Laboratory, M (SD) Bun (mg/dL) 30.7 (22.9) 30.7 (24) .994 Creatinine (mg/dL) 1.4 (1.4) 1.3 (1.2) .762 Albumin (gr/dL) 3.3 (0.5) 3.2 (0.7) .105 Potassium (mEq/L) 4.2 (0.8) 4.3 (0.7) .549 Hemoglobin (g/dL) 11.3 (1.8) 10.9 (2.1) .358 WBC (10ᶺ3/uL) 11.2 (4.6) 11.8 (14.8) .820 Platelets (10ᶺ3/uL) 288.5 (99.8) 232.5 (89.7) .004 TSH (mIU/L) 3.1 (4.5) 2.99 (3.5) .952 Deceased patients, N (%) 2 ( 5 ) 8 ( 14 ) .278 Treatment, N (%) Saline 3% 13 (32) 18 (31) 1.000 fluid restriction 7 (17) 14 (24) .580 Furosemide 13 (32) 20 (34) .990 Drug withdrawal 9 (22) 14 (24) 1.000 saline 0.9% 30 (73) 41 (70) .861 M- (mean), SD (standard deviation), N (number), *Medication causing urinary retention: anticholinergic, alpha agonist, opioid, diuretics A small subset of six patients received no specific treatment for hyponatremia. Four of these patients had urinary retention that was relieved with catheter insertion. The mean sodium improvement in these four patients with urinary retention was 10.8 ± 6.1 mEq/L, substantially higher than the overall study average of 6.4 ± 5.4 mEq/L, although this difference did not reach statistical significance (p = 0.17). Volume status had a modest effect on sodium correction rates. Hypervolemic patients demonstrated slightly slower correction compared to euvolemic and hypovolemic patients (4.3 ± 3.1 mEq/L vs 7.1 ± 6.0 mEq/L vs 7.2 ± 5.5 mEq/L, respectively; p = 0.022). Patients who developed polyuria secondary to post-obstructive diuresis showed more rapid sodium correction. Eleven patients with polyuria had a sodium correction rate of 9.2 ± 6.8 mEq/L compared to 24 patients without polyuria who had a correction rate of 5.8 ± 4.8 mEq/L (p = 0.05). Discussion Hyponatremia is a common medical condition in hospitalized older adults. While previous research has demonstrated an association between hyponatremia and urinary retention ( 8 ), the actual incidence of urinary retention among patients presenting with hyponatremia has not been systematically characterized. In this study, we found a significantly elevated incidence of urinary retention among patients with hyponatremia compared to controls (41% vs 21%, p = 0.004), suggesting that routine assessment for urinary retention should be considered as part of the evaluation of hyponatremic older adults. Our control group demonstrated a notable incidence of urinary retention of 21%, which aligns with previous geriatric literature. Fagard et al. reported a similar incidence of 16% in admitted older patients, though their study used a lower threshold for retention (> 300ml) and excluded patients unable to participate in formal post-void residual assessment ( 5 ). Our study intentionally included patients with cognitive impairment or altered consciousness, reflecting the reality of geriatric practice where such patients represent a significant proportion of those at risk for both hyponatremia and urinary retention. To accommodate this more vulnerable population, we utilized bladder scanning for objective measurement and set our retention threshold at 400ml. This methodological difference likely contributes to our slightly higher baseline incidence and strengthens the clinical applicability of our findings to typical geriatric care settings. Regarding our secondary aim of evaluating whether catheter insertion itself contributes to hyponatremia correction, our findings clarify those of previous research; our earlier study demonstrated that in seven severely hyponatremic patients, urinary catheter insertion was associated with a significantly increased sodium correction rate (9.6 ± 3 mEq/L/48hours) ( 8 ). This larger study did not show this sodium correction when catheter insertion was combined with standard hyponatremia treatment. Importantly however, we observed that patients who developed polyuria following catheter insertion showed significant sodium increases, suggesting that polyuria—rather than catheter insertion per se—may have been the therapeutic mechanism in our previous study. This interpretation is supported by a recent case series describing three patients with severe hyponatremia and urinary retention who all experienced polyuria and rapid sodium correction following catheter insertion, requiring treatment to prevent overcorrection ( 6 ). In our study design, most patients received standard hyponatremia treatment concurrent with catheter insertion, making it difficult to isolate the independent effect of catheter insertion alone. However, we identified four patients for whom catheter insertion was the sole initial treatment, and these patients demonstrated notable sodium correction (10.8 mEq/L) within forty-eight hours. While this observation involves a small number of patients, it provides preliminary evidence that catheter insertion alone may contribute to sodium correction in selected patients with hyponatremia and urinary retention, supporting our hypothesis and warranting further investigation in controlled studies. The pathophysiology underlying the increased incidence of urinary retention in patients with hyponatremia likely involves multiple interconnected mechanisms. First, hyponatremia may directly cause urinary retention through ADH-mediated pathways. Pain from bladder distension in acute urinary retention can stimulate ADH secretion ( 7 ), potentially creating or exacerbating hyponatremia. Supporting this mechanism, 46% (19 of 41) of our patients with urinary retention had SIADH, though we found no correlation between retention volume and sodium levels. Second, hyponatremia may contribute to "functional" urinary retention through its neurological effects. Hyponatremia commonly causes altered mental status, delirium, and impaired mobility in older adults—all factors that can precipitate urinary retention. Based on Fagard et al.'s framework of predisposing and precipitating factors for urinary retention ( 5 ), we propose that hyponatremia serves as a multifactorial precipitant. Beyond cognitive impairment, hyponatremic patients may experience increased urinary output from diuretic therapy (in hypovolemic cases), further compromising their ability to maintain normal voiding patterns. Third, a maladaptive behavioural response may contribute to this association. Patients experiencing oliguria may increase fluid intake believing this will promote urination, inadvertently worsening dilutional hyponatremia. This creates a potentially harmful cycle, as the appropriate therapeutic response to hyponatremia typically involves fluid restriction rather than increased intake ( 14 ). Our study represents the first systematic examination of urinary retention incidence in a large cohort of patients with hyponatremia, with detailed clinical and laboratory data available for comprehensive analysis. Several important limitations warrant consideration. The descriptive study design precluded definitive assessment of interventional effects, particularly the impact of catheter insertion as monotherapy. We did not collect comprehensive clinical data in the control group, limiting our ability to perform detailed comparative analyses. Additionally, we did not systematically evaluate pain as an independent precipitant of SIADH, which may have provided further insights into the ADH-mediated mechanisms we propose. These methodological constraints reflect the challenges of conducting clinical research in complex geriatric patients while maintaining clinical care priorities. Future research should investigate catheter insertion as sole therapy in asymptomatic patients with concurrent hyponatremia and urinary retention through controlled clinical trials. Additionally, a study examining ADH levels across varying retention volumes could provide valuable insights into the pathophysiological relationship between these conditions further informing clinical practice. In summary, there is a significantly higher incidence of urinary retention in patients with hyponatremia which is associated with the severity of hyponatremia. We recommend a routine bladder scan for all patients presenting with hyponatremia and then monitoring for polyuria. A significant predictor of rapid sodium correction is polyuria following urinary catheter insertion. Declarations Previous presentation This work has not been previously presented at any meeting. Preprint publication This work has not been published as a preprint. Corresponding Author Dvorah S. Shapiro, MD Ethics approval and consent to participate: The study was approved by the Ethics Committee of SZMC (Shaare Zedek Medical Center), approval number 0222-22-SZMC, and was conducted in accordance with the Declaration of Helsinki. The need for informed consent was waived by the Ethics Committee, as the study was based on data collected during routine clinical care. Consent for publication Not applicable Competing interests The authors declare that they have no competing interests. Funding: None. Author Contribution oncept and design: D.S.S, R.E, M.S, G.MAcquisition of subjects and/or data: H.M, H.AAnalysis and interpretation of data: D.S.S, R.E, M.S, G.MPreparation of manuscript:D.S.S, R.E, M.S, G.M Acknowledgments Not applicable Clinical trial number : Not applicable Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. References Zhang X, Li X-Y. Prevalence of hyponatremia among older inpatients in a general hospital. Eur Geriatr Med. 2020;11(4):685–92. Adrogué HJ, Madias NE, Hyponatremia. N Engl J Med. 2000;342(21):1581–9. Boyer S, Gayot C, Bimou C, Mergans T, Kajeu P, Castelli M, et al. Prevalence of mild hyponatremia and its association with falls in older adults admitted to an emergency geriatric medicine unit (the MUPA unit). BMC Geriatr. 2019;19(1):265. Hawkins RC. Age and gender as risk factors for hyponatremia and hypernatremia. Clin Chim Acta. 2003;337(1–2):169–72. Fagard K, Hermans K, Deschodt M, Van de Wouwer S, Vander Aa F, Flamaing J. Urinary retention on an acute geriatric hospitalisation unit: prevalence, risk factors and the role of screening, an observational cohort study. Eur Geriatr Med. 2021;12(5):1011–20. van der Bilt F, Alsma J. Hyponatraemia caused by transient syndrome of inappropriate antidiuresis to urinary retention. Intern Med J. 2023;53(2):285–8. Galperin I, Friedmann R, Feldman H, Sonnenblick M. Urinary retention: a cause of hyponatremia? Gerontology. 2007;53(3):121–4. Shapiro DS, Alexandrovich I, Sonnenblick M, Shavit L, Munter G, Friedmann R. Prospective determination of the incidence and severity of hyponatraemia in older hospitalised patients with acute urinary tract obstruction. Age Ageing. 2022;51(1). Schettini DA, Freitas FG, Tomotani DY, Alves JC, Bafi AT, Machado FR. Incidence and risk factors for urinary retention in critically ill patients. Nurs Crit Care. 2019;24(6):355–61. Peterson AC, Smith AR, Fraser MO, Yang CC, DeLancey JOL, Gillespie BW, et al. The Distribution of Post-Void Residual Volumes in People Seeking Care in the Symptoms of Lower Urinary Tract Dysfunction Network Observational Cohort Study With Comparison to Asymptomatic Populations. Urology. 2019;130:22–8. Tolkin L, Vidberg M, Munter G. Basal serum cortisol levels predict a normal response to the Synacthen stimulation test in hospitalised patients. Intern Med J. 2022;52(1):105–9. Spasovski G, Vanholder R, Allolio B, Annane D, Ball S, Bichet D, et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Eur J Endocrinol. 2014;170(3):G1–47. Bhasin B, Velez JCQ. Evaluation of polyuria: the roles of solute loading and water diuresis. Am J Kidney Dis. 2016;67(3):507–11. Pyle R, Scott M, Bartholomew J, McGrath S, Moffett B. Accidental polydipsia and hyponatremia from diphenhydramine urinary retention. Am J Med. 2011;124(10):e5–6. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 15 Oct, 2025 Reviews received at journal 13 Oct, 2025 Reviewers agreed at journal 10 Oct, 2025 Reviewers invited by journal 06 Oct, 2025 Editor assigned by journal 01 Oct, 2025 Editor invited by journal 09 Sep, 2025 Submission checks completed at journal 05 Sep, 2025 First submitted to journal 05 Sep, 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. 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-7228177","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":530707079,"identity":"1ea50d30-0424-428c-915b-4b3e22e891d0","order_by":0,"name":"Dvorah S. Shapiro","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9UlEQVRIiWNgGAWjYDCCAzCSGUh9QIhLyBClhXEGkhYewlqAgBlZGU4tfDeSj3348eeOvDk778PHNn/qovkbmI99/MJggVOL5I205Jm9bc8MdzazGxvntrHlzjjAljxbBo/DDM6cMWbgbTjMuOEwG5t0bgNP7gYGHmNmCQJaGP/8OWwP1mLxR4IILcd7jJl52A4ngrUwsBmAtTB+wKNF8nhbMrNs2+Hknc1szIa9bQm5Mw6zJTMzGODWwneY+TDjmz+HbbfzH2N88ONPXW5/e/Nhxh8VdXK4tCBcCGcxgyLIAI9STC1AwPiDCB2jYBSMglEwYgAAc4hPMdpxzCgAAAAASUVORK5CYII=","orcid":"","institution":"Shaare Zedek Medical Center, Hebrew University-Hadassah Medical School","correspondingAuthor":true,"prefix":"","firstName":"Dvorah","middleName":"S.","lastName":"Shapiro","suffix":""},{"id":530707080,"identity":"2d8b4ea4-5363-44ec-a72d-4d543ab60b5e","order_by":1,"name":"Raphael Ellis","email":"","orcid":"","institution":"Shaare Zedek Medical Center, Hebrew University-Hadassah Medical School","correspondingAuthor":false,"prefix":"","firstName":"Raphael","middleName":"","lastName":"Ellis","suffix":""},{"id":530707081,"identity":"5a313663-06f3-42e8-bb25-0f0517119c30","order_by":2,"name":"Husam Mouhtaseb","email":"","orcid":"","institution":"Shaare Zedek Medical Center, Hebrew University-Hadassah Medical School","correspondingAuthor":false,"prefix":"","firstName":"Husam","middleName":"","lastName":"Mouhtaseb","suffix":""},{"id":530707082,"identity":"9733343a-697d-4580-8831-d34721191043","order_by":3,"name":"Hiba Abdelkareem","email":"","orcid":"","institution":"Shaare Zedek Medical Center, Hebrew University-Hadassah Medical School","correspondingAuthor":false,"prefix":"","firstName":"Hiba","middleName":"","lastName":"Abdelkareem","suffix":""},{"id":530707083,"identity":"68b8fbeb-9cc7-4393-b0be-caa10e8fa602","order_by":4,"name":"Moshe Sonnenblick","email":"","orcid":"","institution":"Shaare Zedek Medical Center, Hebrew University-Hadassah Medical School","correspondingAuthor":false,"prefix":"","firstName":"Moshe","middleName":"","lastName":"Sonnenblick","suffix":""},{"id":530707084,"identity":"74b45b08-180e-46b2-929d-d4aaed772b42","order_by":5,"name":"Gabriel Munter","email":"","orcid":"","institution":"Shaare Zedek Medical Center, Hebrew University-Hadassah Medical School","correspondingAuthor":false,"prefix":"","firstName":"Gabriel","middleName":"","lastName":"Munter","suffix":""}],"badges":[],"createdAt":"2025-07-27 20:23:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7228177/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7228177/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":93761458,"identity":"178f34d7-fc59-4fbf-8e17-15b6f340b509","added_by":"auto","created_at":"2025-10-17 09:49:22","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":41022,"visible":true,"origin":"","legend":"","description":"","filename":"hyponatraemiainolderhospitilsedpatientswithurinaryretention050925.docx","url":"https://assets-eu.researchsquare.com/files/rs-7228177/v1/f6a086c0c80682434590ebdc.docx"},{"id":93761460,"identity":"54b9c172-74fc-4162-a55e-8f06b0a9aef7","added_by":"auto","created_at":"2025-10-17 09:49:22","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":7396,"visible":true,"origin":"","legend":"","description":"","filename":"901488b79a6d46a699fafdb5af49a804.json","url":"https://assets-eu.researchsquare.com/files/rs-7228177/v1/13ee66fc76469a1e2a4888f6.json"},{"id":93761461,"identity":"9805174c-bf2a-471a-80dd-50956dcc677b","added_by":"auto","created_at":"2025-10-17 09:49:22","extension":"xml","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":70781,"visible":true,"origin":"","legend":"","description":"","filename":"901488b79a6d46a699fafdb5af49a8041enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-7228177/v1/502107e7bcde229c0c6183da.xml"},{"id":93762610,"identity":"620be08f-4774-4592-8446-5d9c49281376","added_by":"auto","created_at":"2025-10-17 09:57:22","extension":"xml","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":66631,"visible":true,"origin":"","legend":"","description":"","filename":"901488b79a6d46a699fafdb5af49a8041structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7228177/v1/064fa96fea40ada12d430a28.xml"},{"id":93761462,"identity":"ce727e27-a7cf-4127-96f2-ac4112ed829c","added_by":"auto","created_at":"2025-10-17 09:49:22","extension":"html","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":74865,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7228177/v1/ebcf57e849a49ffbfaf33cba.html"},{"id":93762903,"identity":"95c5c705-3c36-43a4-8eda-1ebf0119d687","added_by":"auto","created_at":"2025-10-17 10:05:22","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":644494,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7228177/v1/1a6b680f-dde3-4681-bcb6-0c2dcb534fbb.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Urinary Retention in Older Adults with Hyponatremia admitted to Acute Medical Wards","fulltext":[{"header":"Key Points","content":"\u003cul type=\"disc\"\u003e\n \u003cli\u003eUrinary retention occurred in 41% of older hyponatremic patients compared to 21% of normonatremic controls, with the highest incidence (44%) in patients with severe hyponatremia (\u0026le;125 mEq/L).\u003c/li\u003e\n \u003cli\u003ePost-obstructive diuresis following urinary catheter insertion was associated with more rapid sodium correction in hyponatremic patients (9.2\u0026plusmn;6.8 mEq/L vs 5.8\u0026plusmn;4.8 mEq/L over 48 hours).\u003c/li\u003e\n \u003cli\u003eRoutine bladder scanning should be considered for all patients presenting with hyponatremia to identify concurrent urinary retention.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eWhy does this paper matter?\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study establishes a clear association between hyponatremia severity and urinary retention in older adults, providing clinicians with evidence to support routine bladder assessment in hyponatremic patients. The findings suggest that identifying and treating urinary retention may influence sodium correction rates, potentially impacting clinical management strategies for this common electrolyte disorder.\u003c/p\u003e"},{"header":"Introduction","content":"\u003cp\u003eHyponatremia and urinary retention represent significant clinical challenges commonly encountered in acute Medical and Geriatric wards (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). The prevalence of hyponatremia is high, affecting approximately one in five older patients (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e), with some studies documenting rates as high as 36\u0026ndash;42% among hospitalized patients (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Similarly, urinary retention is common, with an estimated incidence of one in eight patients (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eWhile several studies have demonstrated an association between these two conditions (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e), the specific incidence of urinary retention among patients presenting with hyponatremia remains inadequately characterized.\u003c/p\u003e\u003cp\u003eOne prospective controlled study (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e) examined the reverse association by analysing the incidence of hyponatremia in patients with acute urinary tract obstruction (aUTO). Although the overall incidence of hyponatremia was comparable between patients with aUTO and controls\u0026mdash;regardless of age, baseline comorbidities, or cause of admission\u0026mdash;important differences emerged upon closer examination. Patients with aUTO demonstrated significantly lower mean sodium levels and a markedly higher incidence of severe hyponatremia compared to controls. Importantly, relief of the urinary obstruction resulted in rapid and significant improvement in serum sodium levels, suggesting a direct pathophysiological relationship between the two conditions.\u003c/p\u003e\u003cp\u003eUnderstanding this bidirectional relationship is crucial for optimizing clinical management and improving patient outcomes in these vulnerable populations.\u003c/p\u003e\u003cp\u003eSupporting evidence comes from a case series conducted on a Geriatric ward, which described six older patients presenting with concurrent hyponatremia and urinary retention (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). In all cases, serum sodium levels normalized and remained stable following foley catheter insertion combined with fluid restriction. Despite extensive diagnostic workups during hospitalization, no alternative etiology for the hyponatremia could be identified beyond the urinary retention itself. Additional anecdotal reports, summarized in two recent studies, have further highlighted the occurrence of hyponatremia in patients with acute urinary tract obstruction, with rapid resolution following relief of the obstruction (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe primary aim of this study was to determine the incidence of urinary retention among patients with hyponatremia by comparing rates between those with severe (\u0026lt;\u0026thinsp;126 mEq/L) and moderate (126\u0026ndash;129 mEq/L) hyponatremia versus patients with normal sodium levels. The secondary aim was to assess whether urinary catheter insertion influenced the rate of sodium correction.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis prospective, observational, single-centre study was conducted at Shaare Zedek Medical Centre (SZMC), Jerusalem, Israel, a university-affiliated 1,000-bed general community hospital, between November 2022 and July 2023. During the study period, general medical patients aged 65 years and older with serum sodium levels\u0026thinsp;\u0026le;\u0026thinsp;129 mEq/L were enrolled. Patients were excluded if they underwent haemodialysis, had a nephrostomy, ileal conduit, or permanent catheter in situ. The control group comprised older patients (\u0026ge;\u0026thinsp;65 years) admitted to the same medical wards during the study period, who had normal sodium levels (135\u0026ndash;145 mEq/L) and were voiding spontaneously without a urinary catheter.\u003c/p\u003e\u003cp\u003eAll patients underwent a bladder scan. Urinary retention was defined as residual volume\u0026thinsp;\u0026gt;\u0026thinsp;400 ml (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e), and patients meeting this criterion had a urinary catheter inserted. Comprehensive demographic and clinical data were collected, including presenting symptoms, medication history (particularly drugs associated with hyponatremia or urinary retention), and physical examination findings. Volemic status was assessed through medical history, physical examination including vital signs, and laboratory investigations.\u003c/p\u003e\u003cp\u003eLaboratory workup included complete blood count, biochemistry with serum osmolality, renal function tests, urinary sodium, and urinary osmolality. Thyroid-stimulating hormone (TSH) levels were obtained in most patients, and cortisol levels were measured when adrenal insufficiency was clinically suspected (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). Most patients underwent chest radiography, with additional imaging studies performed at the discretion of the attending physician.\u003c/p\u003e\u003cp\u003eSyndrome of inappropriate antidiuretic hormone secretion (SIADH) was defined clinically as hypotonic hyponatremia with concentrated urine in a euvolemic patient, after excluding adrenal insufficiency and hypothyroidism (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). Serum sodium levels were repeated within 48 hours of initial measurement. Urine output was monitored following catheter insertion, with post-obstructive diuresis defined as polyuria with urine output exceeding 3 liters per day after catheter insertion (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAll treatments for hyponatremia were systematically recorded, with concurrent therapies documented separately. Treatment modalities included discontinuation of medications associated with hyponatremia, fluid restriction, intravenous 3% saline, intravenous 0.9% saline for hypovolaemia, and diuretics for hypervolaemia.\u003c/p\u003e\u003cp\u003e\u003cb\u003eStatistical Analysis\u003c/b\u003e Continuous variables were presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD), while categorical variables were presented as total number and percentage. Categorical variables were compared between study groups using the Chi-square test. For normally distributed continuous variables, t-test or one-way ANOVA were employed. Comparisons of continuous variables with non-normal distribution were performed using the Mann-Whitney U test. The correlation between residual volume and sodium level was calculated using Pearson correlation analysis.\u003c/p\u003e\u003cp\u003eA two-tailed p-value of \u0026lt;\u0026thinsp;0.05 was considered statistically significant. Statistical analyses were performed using Epi-Info software version 7.2 and SPSS version 25. The study was approved by the Ethics Committee of SZMC, (Shaare Zedek Medical Center), approval number 0222-22-SZMC.\u003c/p\u003e\u003cp\u003eWritten informed consent was not obtained from individual patients, as the study was based on data collected during routine clinical care.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eOne hundred and ninety-nine patients were enrolled in the study: 100 patients with hyponatremia\u0026thinsp;\u0026lt;\u0026thinsp;129 mEq/L (including 70 patients with severe hyponatremia\u0026thinsp;\u0026le;\u0026thinsp;125 mEq/L) and 99 normonatremic controls.\u003c/p\u003e\u003cp\u003ePatient demographics were well-matched between groups, with no significant differences in age or sex distribution (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Although there was a slightly lower proportion of men in the hyponatremia group (33% vs 45%), this difference was not statistically significant. When comparing sex distribution among patients with urinary retention, the proportions were similar between hyponatremic and control groups (33% vs 38% male, p\u0026thinsp;=\u0026thinsp;0.83).\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\u003eThe characteristics of patients according to sodium level\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=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNa\u0026thinsp;\u0026lt;\u0026thinsp;126 mEq/L (n\u0026thinsp;=\u0026thinsp;70)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eNa126-129 mEq/L (n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNa\u0026thinsp;\u0026lt;\u0026thinsp;130 mEq/L (n\u0026thinsp;=\u0026thinsp;100)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNa\u0026thinsp;\u0026ge;\u0026thinsp;135 mEq/L (n\u0026thinsp;=\u0026thinsp;99)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\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\u003eAge (year), Mean (SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e84.4 (8.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e84.9 (7.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e84.6 (8.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e84 (8.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e.618\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex (male) (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e25 (36)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e8 (27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e33 (33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e45(45)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e.098\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNa (mEq/L), M (SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e119.8 (4.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e127.1 (1.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e122 (5.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e139.1 (2.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0005\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUrinary retention (%),\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e31 (44)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e10 (33))\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e41 (41)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e21 (21)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e.004\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMean volume of retention ml M (SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e705 (390)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e749 (301)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e715 (367)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e670 (246)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.63\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003eSD- standard deviation\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003eUrinary retention above 400 ml\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003e* Between research group (Na\u0026thinsp;\u0026lt;\u0026thinsp;130) and compare group (Na\u0026thinsp;\u0026ge;\u0026thinsp;135 mEq/L)\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eWe reviewed medications that may cause urinary retention, including anticholinergic drugs, alpha agonists, opioids, and diuretics. The use of these medications did not differ significantly between patients with and without urinary retention across all 199 patients (52% vs 55%, p\u0026thinsp;=\u0026thinsp;0.61).\u003c/p\u003e\u003cp\u003eThe incidence of urinary retention was significantly higher in hyponatremic patients compared to those with normal sodium levels (41% vs 21%, p\u0026thinsp;=\u0026thinsp;0.004). Among the 70 patients with severe hyponatremia, the incidence of urinary retention was even higher at 44% (p\u0026thinsp;=\u0026thinsp;0.004).\u003c/p\u003e\u003cp\u003eAmong the 41 hyponatremic patients with urinary retention, the mean retention volume was 715\u0026thinsp;\u0026plusmn;\u0026thinsp;367 ml, which was comparable to the retention volume in 21 normonatremic patients with urinary retention (670\u0026thinsp;\u0026plusmn;\u0026thinsp;246 ml, p\u0026thinsp;=\u0026thinsp;0.61). There was no correlation between retention volume and sodium level (r=-0.063, p\u0026thinsp;=\u0026thinsp;0.63).\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e compares hyponatremic patients with and without urinary retention. These subgroups were similar in age, gender, and comorbidity burden, with no differences in the use of medications commonly causing hyponatremia or medications that may cause urinary retention. Similarly, there was no difference in volume status or laboratory results. Mean baseline sodium levels were comparable between groups (123 mEq/L vs 121 mEq/L, p\u0026thinsp;=\u0026thinsp;0.178). Of the 41 patients with hyponatremia and urinary retention, 19 (46.3%) had SIADH.\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\u003e\u0026ndash;Hyponatremic patients with and without urinary retention (above 400 ml)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\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\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUrinary retention\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYes (n\u0026thinsp;=\u0026thinsp;41)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNo (n\u0026thinsp;=\u0026thinsp;59)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\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\u003eAge(year), M (SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e84.5 (8.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e84.7 (8.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.900\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex, (male, N (%))\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14 (34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e19 (32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.000\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eComorbidities, N (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDiabetes mellitus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13 (32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e18 (31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.000\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypertension\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30 (73)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e46 (78)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.753\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCongestive heart failure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11 (27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e19 (32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.723\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCerebrovascular accident\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4 (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9 (15)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.616\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChronic kidney disease\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9 (22)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e12 (20)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.000\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMalignancy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4 (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9 (15)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.616\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHospitalization reason,\u003c/p\u003e\u003cp\u003eN (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.945\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHyponatremia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8 (20)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14 (24)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFall\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5 (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7 (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCardiovascular disease\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6 (15)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11 (19)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInfection\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11 (27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14 (24)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOther\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11 (27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13 (22)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMedication, N (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThiazide\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2 (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4 (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.000\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSSRI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5 (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5 (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.786\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOpioids\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4 (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.608\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMedication causing\u003c/p\u003e\u003cp\u003eUrinary retention*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17(42)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e29(49)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.448\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVolemic status, N (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.215\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEuvolemic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21 (51)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25 (42)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypervolemic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e12 (29)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13 (22)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypovolemic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8 (20)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21 (36)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAdmission Na (mEq/L),\u003c/p\u003e\u003cp\u003eMean (SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e121 (5.56)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e123 (4.95)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.178\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAdmission NA\u0026thinsp;\u0026le;\u0026thinsp;125, N(%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30 (73)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e36 (61)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.295\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNA delta (mEq/L) (48 hours), M (SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.8 (5.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6.1 (5.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.518\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePost Micturition Volume (ml), M (SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e715(367)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e151(116)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.005\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLaboratory, M (SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBun (mg/dL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30.7 (22.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e30.7 (24)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.994\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCreatinine (mg/dL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.4 (1.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.3 (1.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.762\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAlbumin (gr/dL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.3 (0.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.2 (0.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.105\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePotassium (mEq/L)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.2 (0.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.3 (0.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.549\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHemoglobin (g/dL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11.3 (1.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10.9 (2.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.358\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWBC (10ᶺ3/uL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11.2 (4.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11.8 (14.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.820\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePlatelets (10ᶺ3/uL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e288.5 (99.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e232.5 (89.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.004\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTSH (mIU/L)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.1 (4.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.99 (3.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.952\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDeceased patients, N (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2 (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8 (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.278\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatment, N (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSaline 3%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13 (32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e18 (31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.000\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003efluid restriction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7 (17)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14 (24)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.580\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFurosemide\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13 (32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20 (34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.990\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDrug withdrawal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9 (22)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14 (24)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.000\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003esaline 0.9%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30 (73)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e41 (70)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.861\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eM- (mean), SD (standard deviation), N (number),\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003e*Medication causing urinary retention: anticholinergic, alpha agonist, opioid, diuretics\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eA small subset of six patients received no specific treatment for hyponatremia. Four of these patients had urinary retention that was relieved with catheter insertion. The mean sodium improvement in these four patients with urinary retention was 10.8\u0026thinsp;\u0026plusmn;\u0026thinsp;6.1 mEq/L, substantially higher than the overall study average of 6.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.4 mEq/L, although this difference did not reach statistical significance (p\u0026thinsp;=\u0026thinsp;0.17).\u003c/p\u003e\u003cp\u003eVolume status had a modest effect on sodium correction rates. Hypervolemic patients demonstrated slightly slower correction compared to euvolemic and hypovolemic patients (4.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1 mEq/L vs 7.1\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0 mEq/L vs 7.2\u0026thinsp;\u0026plusmn;\u0026thinsp;5.5 mEq/L, respectively; p\u0026thinsp;=\u0026thinsp;0.022).\u003c/p\u003e\u003cp\u003ePatients who developed polyuria secondary to post-obstructive diuresis showed more rapid sodium correction. Eleven patients with polyuria had a sodium correction rate of 9.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.8 mEq/L compared to 24 patients without polyuria who had a correction rate of 5.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.8 mEq/L (p\u0026thinsp;=\u0026thinsp;0.05).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eHyponatremia is a common medical condition in hospitalized older adults. While previous research has demonstrated an association between hyponatremia and urinary retention (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e), the actual incidence of urinary retention among patients presenting with hyponatremia has not been systematically characterized. In this study, we found a significantly elevated incidence of urinary retention among patients with hyponatremia compared to controls (41% vs 21%, p\u0026thinsp;=\u0026thinsp;0.004), suggesting that routine assessment for urinary retention should be considered as part of the evaluation of hyponatremic older adults.\u003c/p\u003e\u003cp\u003eOur control group demonstrated a notable incidence of urinary retention of 21%, which aligns with previous geriatric literature. Fagard et al. reported a similar incidence of 16% in admitted older patients, though their study used a lower threshold for retention (\u0026gt;\u0026thinsp;300ml) and excluded patients unable to participate in formal post-void residual assessment (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). Our study intentionally included patients with cognitive impairment or altered consciousness, reflecting the reality of geriatric practice where such patients represent a significant proportion of those at risk for both hyponatremia and urinary retention. To accommodate this more vulnerable population, we utilized bladder scanning for objective measurement and set our retention threshold at 400ml. This methodological difference likely contributes to our slightly higher baseline incidence and strengthens the clinical applicability of our findings to typical geriatric care settings.\u003c/p\u003e\u003cp\u003eRegarding our secondary aim of evaluating whether catheter insertion itself contributes to hyponatremia correction, our findings clarify those of previous research; our earlier study demonstrated that in seven severely hyponatremic patients, urinary catheter insertion was associated with a significantly increased sodium correction rate (9.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3 mEq/L/48hours) (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). This larger study did not show this sodium correction when catheter insertion was combined with standard hyponatremia treatment. Importantly however, we observed that patients who developed polyuria following catheter insertion showed significant sodium increases, suggesting that polyuria\u0026mdash;rather than catheter insertion per se\u0026mdash;may have been the therapeutic mechanism in our previous study. This interpretation is supported by a recent case series describing three patients with severe hyponatremia and urinary retention who all experienced polyuria and rapid sodium correction following catheter insertion, requiring treatment to prevent overcorrection (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn our study design, most patients received standard hyponatremia treatment concurrent with catheter insertion, making it difficult to isolate the independent effect of catheter insertion alone. However, we identified four patients for whom catheter insertion was the sole initial treatment, and these patients demonstrated notable sodium correction (10.8 mEq/L) within forty-eight hours. While this observation involves a small number of patients, it provides preliminary evidence that catheter insertion alone may contribute to sodium correction in selected patients with hyponatremia and urinary retention, supporting our hypothesis and warranting further investigation in controlled studies.\u003c/p\u003e\u003cp\u003eThe pathophysiology underlying the increased incidence of urinary retention in patients with hyponatremia likely involves multiple interconnected mechanisms. First, hyponatremia may directly cause urinary retention through ADH-mediated pathways. Pain from bladder distension in acute urinary retention can stimulate ADH secretion (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e), potentially creating or exacerbating hyponatremia. Supporting this mechanism, 46% (19 of 41) of our patients with urinary retention had SIADH, though we found no correlation between retention volume and sodium levels.\u003c/p\u003e\u003cp\u003eSecond, hyponatremia may contribute to \"functional\" urinary retention through its neurological effects. Hyponatremia commonly causes altered mental status, delirium, and impaired mobility in older adults\u0026mdash;all factors that can precipitate urinary retention. Based on Fagard et al.'s framework of predisposing and precipitating factors for urinary retention (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e), we propose that hyponatremia serves as a multifactorial precipitant. Beyond cognitive impairment, hyponatremic patients may experience increased urinary output from diuretic therapy (in hypovolemic cases), further compromising their ability to maintain normal voiding patterns.\u003c/p\u003e\u003cp\u003eThird, a maladaptive behavioural response may contribute to this association. Patients experiencing oliguria may increase fluid intake believing this will promote urination, inadvertently worsening dilutional hyponatremia. This creates a potentially harmful cycle, as the appropriate therapeutic response to hyponatremia typically involves fluid restriction rather than increased intake (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eOur study represents the first systematic examination of urinary retention incidence in a large cohort of patients with hyponatremia, with detailed clinical and laboratory data available for comprehensive analysis.\u003c/p\u003e\u003cp\u003eSeveral important limitations warrant consideration. The descriptive study design precluded definitive assessment of interventional effects, particularly the impact of catheter insertion as monotherapy. We did not collect comprehensive clinical data in the control group, limiting our ability to perform detailed comparative analyses. Additionally, we did not systematically evaluate pain as an independent precipitant of SIADH, which may have provided further insights into the ADH-mediated mechanisms we propose. These methodological constraints reflect the challenges of conducting clinical research in complex geriatric patients while maintaining clinical care priorities.\u003c/p\u003e\u003cp\u003eFuture research should investigate catheter insertion as sole therapy in asymptomatic patients with concurrent hyponatremia and urinary retention through controlled clinical trials. Additionally, a study examining ADH levels across varying retention volumes could provide valuable insights into the pathophysiological relationship between these conditions further informing clinical practice.\u003c/p\u003e\u003cp\u003eIn summary, there is a significantly higher incidence of urinary retention in patients with hyponatremia which is associated with the severity of hyponatremia. We recommend a routine bladder scan for all patients presenting with hyponatremia and then monitoring for polyuria. A significant predictor of rapid sodium correction is polyuria following urinary catheter insertion.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003ePrevious presentation\u003c/h2\u003e\u003cp\u003eThis work has not been previously presented at any meeting.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003ePreprint publication\u003c/strong\u003e\u003cp\u003eThis work has not been published as a preprint.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCorresponding Author\u003c/strong\u003e\u003cp\u003eDvorah S. Shapiro, MD\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e\u003cp\u003e The study was approved by the Ethics Committee of SZMC (Shaare Zedek Medical Center), approval number 0222-22-SZMC, and was conducted in accordance with the Declaration of Helsinki. The need for informed consent was waived by the Ethics Committee, as the study was based on data collected during routine clinical care.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003cp\u003eNot applicable\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003ch2\u003eCompeting interests\u003c/h2\u003e\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e\u003cp\u003eNone.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eoncept and design: D.S.S, R.E, M.S, G.MAcquisition of subjects and/or data: H.M, H.AAnalysis and interpretation of data: D.S.S, R.E, M.S, G.MPreparation of manuscript:D.S.S, R.E, M.S, G.M\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e\u003cp\u003eNot applicable\u003c/p\u003e\u003cp\u003e\u003cb\u003eClinical trial number\u003c/b\u003e:\u003c/p\u003e\u003cp\u003eNot applicable\u003c/p\u003e\u003ch2\u003eAvailability of data and materials\u003c/h2\u003e\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eZhang X, Li X-Y. Prevalence of hyponatremia among older inpatients in a general hospital. Eur Geriatr Med. 2020;11(4):685\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAdrogu\u0026eacute; HJ, Madias NE, Hyponatremia. N Engl J Med. 2000;342(21):1581\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBoyer S, Gayot C, Bimou C, Mergans T, Kajeu P, Castelli M, et al. Prevalence of mild hyponatremia and its association with falls in older adults admitted to an emergency geriatric medicine unit (the MUPA unit). BMC Geriatr. 2019;19(1):265.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHawkins RC. Age and gender as risk factors for hyponatremia and hypernatremia. Clin Chim Acta. 2003;337(1\u0026ndash;2):169\u0026ndash;72.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFagard K, Hermans K, Deschodt M, Van de Wouwer S, Vander Aa F, Flamaing J. Urinary retention on an acute geriatric hospitalisation unit: prevalence, risk factors and the role of screening, an observational cohort study. Eur Geriatr Med. 2021;12(5):1011\u0026ndash;20.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003evan der Bilt F, Alsma J. Hyponatraemia caused by transient syndrome of inappropriate antidiuresis to urinary retention. Intern Med J. 2023;53(2):285\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGalperin I, Friedmann R, Feldman H, Sonnenblick M. Urinary retention: a cause of hyponatremia? Gerontology. 2007;53(3):121\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShapiro DS, Alexandrovich I, Sonnenblick M, Shavit L, Munter G, Friedmann R. Prospective determination of the incidence and severity of hyponatraemia in older hospitalised patients with acute urinary tract obstruction. Age Ageing. 2022;51(1).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSchettini DA, Freitas FG, Tomotani DY, Alves JC, Bafi AT, Machado FR. Incidence and risk factors for urinary retention in critically ill patients. Nurs Crit Care. 2019;24(6):355\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePeterson AC, Smith AR, Fraser MO, Yang CC, DeLancey JOL, Gillespie BW, et al. The Distribution of Post-Void Residual Volumes in People Seeking Care in the Symptoms of Lower Urinary Tract Dysfunction Network Observational Cohort Study With Comparison to Asymptomatic Populations. Urology. 2019;130:22\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTolkin L, Vidberg M, Munter G. Basal serum cortisol levels predict a normal response to the Synacthen stimulation test in hospitalised patients. Intern Med J. 2022;52(1):105\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSpasovski G, Vanholder R, Allolio B, Annane D, Ball S, Bichet D, et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Eur J Endocrinol. 2014;170(3):G1\u0026ndash;47.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBhasin B, Velez JCQ. Evaluation of polyuria: the roles of solute loading and water diuresis. Am J Kidney Dis. 2016;67(3):507\u0026ndash;11.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePyle R, Scott M, Bartholomew J, McGrath S, Moffett B. Accidental polydipsia and hyponatremia from diphenhydramine urinary retention. Am J Med. 2011;124(10):e5\u0026ndash;6.\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-geriatrics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bgtc","sideBox":"Learn more about [BMC Geriatrics](http://bmcgeriatr.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bgtc/default.aspx","title":"BMC Geriatrics","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Hyponatremia, urinary retention, post-obstructive diuresis","lastPublishedDoi":"10.21203/rs.3.rs-7228177/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7228177/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e Hyponatremia and urinary retention are common medical problems. While associations between the two are documented, research has not clearly established the incidence of urinary retention in hyponatremic patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eObjectives\u003c/strong\u003e To determine the incidence of urinary retention in hyponatremic patients and assess whether urinary catheter insertion affects the sodium correction rate.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e A prospective, single centre, observational study including patients hospitalized in Internal Medicine and Geriatric wards. A total of 199 older patients (mean age 84.4, 39% men) were investigated: 100 with hyponatremia ≤129 mEq/L (of these, 70 had severe hyponatremia ≤125 mEq/L) and 99 normonatremic controls. The incidence of urinary retention was checked in all groups. Hyponatremic patients underwent complete assessment for the cause of hyponatremia and sodium levels were followed up for 48 hours.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e There was a marked increase in the incidence of urinary retention in older hyponatremic patients compared to those with normal sodium levels (41% vs 21%, p=0.004). The difference was even greater when comparing those with severe hyponatremia to controls (44% vs 21%, p=0.001). Among hyponatremic patients with and without urinary retention, there was no difference in sodium correction rate between the two groups. Patients with polyuria secondary to post-obstructive diuresis had more rapid sodium correction (9.2±6.8 mEq/L vs 5.8±4.8 mEq/L, p=0.05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e There was a significantly higher incidence of urinary retention in older patients with hyponatremia, which correlates with hyponatremia severity. Post-obstructive diuresis following catheter insertion is associated with more rapid sodium correction. We recommend routine bladder scanning for all patients with hyponatremia.\u003c/p\u003e","manuscriptTitle":"Urinary Retention in Older Adults with Hyponatremia admitted to Acute Medical Wards","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-17 09:49:17","doi":"10.21203/rs.3.rs-7228177/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"244781127107671079213488012848210875916","date":"2025-10-16T03:19:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-13T14:29:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"180971350786571032020429158073363452658","date":"2025-10-10T12:26:45+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-06T14:05:13+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-01T09:31:28+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-09-09T07:36:11+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-05T07:01:03+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Geriatrics","date":"2025-09-05T06:58:16+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-geriatrics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bgtc","sideBox":"Learn more about [BMC Geriatrics](http://bmcgeriatr.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bgtc/default.aspx","title":"BMC Geriatrics","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"038289a1-e5b7-4532-a1bf-247a67ed21db","owner":[],"postedDate":"October 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-10-17T09:49:17+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-17 09:49:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7228177","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7228177","identity":"rs-7228177","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}