Abstract: TH-PO0403
Effect of a High-Citrate Beverage on Urine pH in Cystine and Uric Acid Stone Formers
Session Information
- Fluid, Electrolyte, and Acid-Base Disorders: Clinical - 1
November 06, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Fluid, Electrolytes, and Acid-Base Disorders
- 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical
Authors
- Patel, Anuj A., Northwell Health, New Hyde Park, New York, United States
- Modersitzki, Frank, NYU Langone Health, New York, New York, United States
- Shekar, Niveda, NYU Langone Health, New York, New York, United States
- Goldfarb, David S., NYU Langone Health, New York, New York, United States
Background
Alkalinization of urine is important in preventing recurrence of cystine and uric acid stones. In clinical practice we often find nonadherence to commonly prescribed potassium citrate pills due to their size and GI side effects. Moonstone Stone Stopper (MSS), a patented high citrate beverage, is the only over-the-counter preparation that has been shown to effectively increase urine pH in patients with calcium stones (1) . In this study we examine its effect on urine pH in cystine and uric acid stone formers.
Methods
19 participants were enrolled in the study (12 cystine CSF, 7 uric acid UASF). Each participant was randomly assigned to either MSS or water phase and then switched to the opposite phase. Participants drank either 500 ml of water or MSS twice per day for 7 days along with ad lib fluids. The participants’ ad lib diets were replicated on days 6 and 7 of each period. 24-hour urine collection was done on day 7. All other alkali supplements were discontinued during the study. Urine chemistry was analyzed by Litholink (Itasca, IL). Daily dose of MSS comprised of 60Meq net alkali.
Results
Urine volume ( and cystine excretion in CSF) did not change between two periods demonstrating that participants successfully replicated diet and fluid intake. The primary outcome, urine pH, increased for all cystine and uric acid stone formers together (Table 1). The effect in CSF alone was statistically significant, but not in UASF. Patients tolerated therapy with MSS well with no adverseevents or discontinuations.
Conclusion
In comparison to water, MSS significantly increased urine pH in combined groups. The rise in urine pH was noted in all CSF and 5 of 7 UASF (NS due to small sample size). MSS could serve as a well-tolerated alternative therapy for raising urinary pH in patients with cystine and uric acid stones.
(1) Goldfarb DS, Modersitzki F, Asplin JR et. al. Effect of a high-citrate beverage on urine chemistry in patients with calcium kidney stones. Urolithiasis. 2023;51(1):96.
Table 1: Effect of water versus MSS on urine pH
| Urine pH | Urine Volume | |
| CSF Water | 6.60 ± 0.50 | 3.02 ± 1.20 |
| CSF MMS | 7.13 ± 0.29 (Delta 0.53, p 0.004) | 3.30 ± 1.15 |
| UASF Water | 5.76 ± 0.64 | 2.36 ± 0.75 |
| UASF MSS | 6.15 ± 0.63 (Delta 0.39, p 0.272) | 2.01 ± 0.79 |