Investigating fluid intake in an underserved community: what factors are associated with low urine volume on 24-hour urine collection?

• Published in: Journal of endourology
• Main Authors: Ghiraldi, Eric, Nourian, Alex, Chen, Michelle, Friedlander, Justin
• Format: Journal Article
• Language: English
• Published: United States 01.11.2021
• ISSN: 1557-900X
• DOI: 10.1089/end.2020.0879

Background Stone prevention is dependent on high fluid intake, with evidence that low urine volume (LUV) can promote nephrolithiasis in the absence of other metabolic abnormalities. Herein, we investigate patient-related factors associated with LUV on initial 24-hour urine collection in an underserved population. Materials and Methods A retrospective chart review was performed of patients treated by a single surgeon for nephrolithiasis from August 2014-January 2019. Patients who submitted 24-hour urine samples were divided into two groups based on whether their initial collection was greater than two liters or not. Factors associated with 24-hour urine volume were analyzed using bivariate and multivariate analyses. As a secondary outcome, we investigated factors associated with corrected 24-hour urine volume on repeat 24-hour urine collection. Results Two-hundred eight patients (45.1%) submitted 24-hour urine collections, 63.9% (133/208) of which demonstrated urine volume < 2 liters. LUV was more common in females (77.1% vs. 49.5%; p=0.001), and patients with no insurance and Medicaid (no insurance (100%) vs. Medicaid (74.1%) vs. Medicare/private (58.6%); p=0.02). Female gender and insurance status were independent predictors of LUV on multivariable analysis. 39.5% (17/43) of patients with LUV who provided a subsequent collection were able to correct their urine volume. Patients who successfully improved their LUV were older (58.5 vs. 45.9 years, p=0.0149), and more likely to have surgical intervention for their kidney stones (94.1% vs. 53.8%, p=0.006). In our multivariable analysis, surgical intervention was associated with correcting urine volume. Conclusion Female patients and those with no insurance or Medicaid were more likely to have LUV on an initial 24-hour urine collection. Further research into barriers to fluid intake is important for these two groups, along with directed patient education on strategies for increasing fluid intake.