MP33-16 ARE SPOT URINARY DIPSTICK PH VALUES RELIABLY COMPARABLE TO COMMERCIAL 24-HOUR URINARY PH?

Abstract

You have accessJournal of UrologyStone Disease: Basic Research I1 Apr 2015MP33-16 ARE SPOT URINARY DIPSTICK PH VALUES RELIABLY COMPARABLE TO COMMERCIAL 24-HOUR URINARY PH? William Shi, Daniel L. Miller, David L. Wenzler, Angela Wang, and Roger L. Sur William ShiWilliam Shi More articles by this author , Daniel L. MillerDaniel L. Miller More articles by this author , David L. WenzlerDavid L. Wenzler More articles by this author , Angela WangAngela Wang More articles by this author , and Roger L. SurRoger L. Sur More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.577AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Urine pH is a valuable measure of kidney stone risk and for monitoring response to treatment. Spot urinary dipsticks are convenient tools to measure pH but may not reliably reflect true urine pH. Prior work has evaluated spot urinary dipstick against pH meter but not against commercial 24-hour urinary pH. The objective of this study was to determine the accuracy of spot urine dipstick pH compared to 24-hour urine pH in guiding kidney stone risk assessment. METHODS Kidney stone patients undergoing a 24-hour urine collection as a part of their routine evaluation were prospectively enrolled. Subjects were instructed to take digital time, date-stamped images of dipsticks (Chemstrip 10SG, Roche Pharmaceutical) from their first 3 voids concurrently with their 24-hour collection. We then compared the individual and mean pH from the dipstick readings (made by WS) with the 24-hour urine pH (electrochemical pH meter, Litholink). Using the 24-hour urine pH, the cohort was divided into 3 groups—acidic (pH<=6.0), mid-range (pH 6.0-7.0), and basic (pH>7.0) to assess the variability of dipstick accuracy in different pH ranges. The dipstick accuracy was defined as the percentage of mean dipstick pH measurements within 0.5 units of the 24-hour urine pH. This test was repeated for spot dipstick pH measurements. Pearson's correlation coefficient was used to compare mean dipstick and 24-hour urine pH. RESULTS 43 subjects were enrolled and 15 subjects completed both their spot urinary checks and 24-hour urine collection. 9/15 total subjects had mean urinary pH values within 0.5 units of their 24 hour urine pH values. By contrast, 3/15, 2/15, and 3/15 total subjects had spot urinary pH within 0.5 units for their first, second, and third individual voids. In the acidic, midrange, and basic subgroups 3/5, 5/8, and 1/2 subjects, respectively, had mean urinary pH values within 0.5 units of the 24-hour urine pH. Pearson correlation coefficient for the mean urinary dipstick pH and 24-hour urine pH was 0.79 (p<0.01) CONCLUSIONS In our study, single spot dipstick pH readings did not accurately represent 24-hour urine pH. The mean of 3 dipstick readings was more accurate (60%), indicating that mean pH may be more applicable in monitoring the pH of patients with nephrolithiasis. The results should also serve as a caution to urologists using clinic spot urinary dipstick measurement to base their metabolic therapy. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e379 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information William Shi More articles by this author Daniel L. Miller More articles by this author David L. Wenzler More articles by this author Angela Wang More articles by this author Roger L. Sur More articles by this author Expand All Advertisement Advertisement PDF DownloadLoading ...