You have accessJournal of UrologyStone Disease: Evaluation I1 Apr 2015MP75-09 HOW MUCH INFORMATION IS LOST WHEN ONLY ONE 24-HOUR URINE IS COLLECTED AS PART OF THE INITIAL METABOLIC EVALUATION? Abdulrahman Alruwaily, Casey Dauw, Maggie Bierlein, John Asplin, Ghani Khurshid, J. Stuart Wolf Jr, and John Hollingsworth Abdulrahman AlruwailyAbdulrahman Alruwaily More articles by this author , Casey DauwCasey Dauw More articles by this author , Maggie BierleinMaggie Bierlein More articles by this author , John AsplinJohn Asplin More articles by this author , Ghani KhurshidGhani Khurshid More articles by this author , J. Stuart Wolf JrJ. Stuart Wolf Jr More articles by this author , and John HollingsworthJohn Hollingsworth More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.2706AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES During the initial metabolic evaluation, the need for one versus two 24-hour urine collections is debated. While data suggest that mean urine biochemistries are similar on two consecutive samples, it remains unknown how much, if any, information is lost when only one is collected. To fill this knowledge gap, we conducted a study using data from a large central laboratory that provides 24-hour urine services to kidney stone patients. METHODS Using analytical files from Litholink (1995-2013), we identified adults with kidney stones, who underwent initial metabolic testing. Next, we determined the subset of patients that collected two 24-hour urine samples with urine creatinine varying by 10% or less during a seven-day time window. We then analyzed the urinary biochemistry profiles, comparing differences in means between the two samples. Finally, we calculated the mean absolute value of the difference between samples, as well as the percent difference for individual urine parameters (calcium, citrate, oxalate uric acid, and volume). RESULTS We identified 32,138 patients meeting our eligibility criteria. Consistent with prior studies, we found that the overall means for individual urine parameters did not vary significantly between samples; however, the mean absolute difference did (P<0.001 for each comparison). The Table shows the percentage of patients with a given percent difference between samples for each urine parameter. For example, nearly one in three patients had a 30% or more difference in urine calcium and volume between two consecutive samples. We noted that inconsistencies between samples often involved multiple parameters. For instance, 29% and 25% of patients had a 20% difference in two and three or more parameters, respectively. CONCLUSIONS We observed substantial differences between consecutive 24-hour urine samples that could affect provider decision-making. In light of these findings, providers must weigh the information lost from only one collection versus the burden to the patient of collecting two. The percentage of patients with a given percent difference between two samples Parameter % Difference between Consecutive Samples More than 20% More than 30% More than 40% More than 50% Calcium 48.3% 30.1% 17.7% 9.9% Citrate 31.5% 16.2% 8.5% 5.0% Oxalate 30.4% 14.2% 6.3% 2.9% Uric Acid 20.7% 8.0% 3.6% 2.0% Volume 42.6% 25.0% 13.9% 7.3% © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e950 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Abdulrahman Alruwaily More articles by this author Casey Dauw More articles by this author Maggie Bierlein More articles by this author John Asplin More articles by this author Ghani Khurshid More articles by this author J. Stuart Wolf Jr More articles by this author John Hollingsworth More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...