MP75-07 OVER OR UNDER 24-HOUR URINE COLLECTION: CAN ADJUSTMENTS BE MADE TO AVOID REPEAT COLLECTION? (2015)

You have accessJournal of UrologyStone Disease: Evaluation I1 Apr 2015MP75-07 OVER OR UNDER 24-HOUR URINE COLLECTION: CAN ADJUSTMENTS BE MADE TO AVOID REPEAT COLLECTION? Tom Sanford, Krishna Ramaswamy, Tom Chi, and Marshall Stoller Tom SanfordTom Sanford More articles by this author , Krishna RamaswamyKrishna Ramaswamy More articles by this author , Tom ChiTom Chi More articles by this author , and Marshall StollerMarshall Stoller More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.2704AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Twenty four hour urine metabolic evaluation is used in the management of urolithiasis, where creatinine and body weight determine adequacy of collection. Repeat 24-hour urine testing is routine when completeness (over or under collection) is questioned. Patients dislike these tests; they are cumbersome and bothersome. The purpose of this study was to evaluate the impact of over/under collections and whether adjustments can be made to avoid repeat collections. METHODS A retrospective study of the initial 24-hour urine collection for 909 stone-forming men from our institution was undertaken. Mean and standard deviations (SD) were calculated for urinary parameters (calcium, oxalate, sodium, and uric acid) and compared. T-tests were used to evaluate for differences between urinary parameters of patients who had 24-hour creatinine values near the mean compared to patients who had 24-hour creatinine values further away from the mean in a step-wise fashion. Linear regression was used to evaluate the relationship between urinary parameters and creatinine standard deviation values. RESULTS 400 (44%) patients had over- or under-collection of their 24 hour urine according to the reference range of 20-25 mg/kg/24 hours. The overall mean 24-hour creatinine, corrected for weight, was 21 mg/kg (SD 4.9). Comparing patients with 24-hour creatinine values more than 0.5 standard deviation (SD) from the mean with those within 0.5 SD of the mean revealed linear relationships. For each SD increase or decrease from the mean, the urinary calcium value changed by 48mg/24hr (p<0.01). Statistically significant linear relationships were also observed for oxalate (p<0.01), sodium (p<0.01), and uric acid (p<0.01) (Figure 1). CONCLUSIONS Significant differences in 24-hour urine parameters were noted when patients' urinary parameters near the mean were compared with parameters outside of 0.5 SD from the mean. Many urinary variables demonstrated strong linear relationships compared with mean values when originating from under- and over-collected specimens. This illustrates the potential for adjusting 24-hour urine values rather than repeating cumbersome 24-hour collections. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e949-e950 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Tom Sanford More articles by this author Krishna Ramaswamy More articles by this author Tom Chi More articles by this author Marshall Stoller More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...