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EAU 2018: Comparison of Potassium Citrate, Citric Acid and Placebo on Calcium Phosphate Stones Recurrence: Preliminary Results

Copenhagen, Denmark (UroToday.com) Dr. Doizi, clinical urologist from the University of Texas Southwestern Medical Center in Dallas, U.S.A., presented data collected regarding medicinal supplements and their potential relevance of calcium phosphate (CaP) stone recurrence. To date, there has not been a study that effectively correlated a specific medication to the prevention of CaP urinary stone recurrence. Due to previous knowledge of potassium citrate (KCit) and its ability to lower urine calcium and enhance urine citrate excretion, it was hypothesized by Dr. Doizi that KCit may protect against CaP stone formation. However, KCit also raises urine pH which could actually increase CaP saturation and even the stone burden. Additionally, Citric Acid (CitA) has the potential to raise urine citrate, similarly to KCit, but does not raise urine pH. Therefore, in this study, both KCit and CitA were assessed in order to determine whether or not these medications would result in a reduced risk for CaP recurrent stone formation.

The study consisted of a double blind, randomized, placebo controlled, cross-over, metabolic assessment of 13 CaP stone formers with hypercalciuria. These patients were evaluated at the end of three 1-week phases of study during which they took assigned study medications and consumed a fixed metabolic diet. These medications consisted of Citric Acid (CitA), 30 mEq twice daily, Potassium Citrate (KCit), 20 mEq twice daily, or matching placebo. Patients had a 24 hour urine collected for measurement of urine chemistry and calculation of CaP saturation in regard to relative superasaturation ratio (RSR).

Following completion of the study, it was determined that CitA did not significantly alter urine citrate or other urinary parameters when compared to the placebo. However, when compared with placebo and CitA, KCit significantly increased urine citrate and urine pH while marginally lowering urine calcium. Bushite crystal growth, however, had no significance between either medications and the placebo. At the conclusion of his presentation, Dr. Doizi explained to the audience that CitA prescribed at 60 mEq/day is unlikely to significantly alter CaP stone formation in current stone forming patients. He did explain, though, that the long-term impact of KCit on CaP stone recurrence in normocalciuric CaP stone formers needs to be studied further.

Speaker: S. Doizi

Authors: Doizi S. , Poindexter J. , Pearle M. , Sakhaee K. , Maalouf N.

Written by: Zachary Valley, Department of Urology, University of California-Irvine, at the 2018 European Association of Urology Meeting EAU18, 16-20 March, 2018 Copenhagen, Denmark