Medical treatment of uric acid kidney stones.

Introduction: The prevalence of uric acid (UA) stones increases regularly due to its high correlation with obesity, hypertension, metabolic syndrome, type 2 diabetes, and aging. Uric acid stone formation is mainly due to an acidic urinary pH secondary to an impaired urinary ammonium availability responsible for UA rather than soluble urate excretion. Alkalization of urine is therefore advocated to prevent UA crystallization and considered effective therapy.

Methods: We report a large series of 120 patients with UA lithiasis who were successfully treated with potassium (K)-citrate for stone dissolution (n=75) and/or stone recurrence prevention (n=45) without any urologic intervention, with a median 3.14 years followup. The K-citrate was diluted in 1.5 L of water, avoiding gastrointestinal disorders.

Results: Among 75 patients having stones in their kidney at initiation of therapy, a complete chemolysis was obtained in 88% of cases. Stone risk factors decreased under treatment, mainly due to increased diuresis, urinary pH, and citrate excretion. Treatment was stopped in only 2% of patients due to side effects, with no hyperkalemia onset despite a median urinary potassium increase of 44 mmol/day.

Conclusions: Contrary to other reports, our data show that medical treatment of UA kidney stones is well-tolerated and efficient if regular monitoring of urinary pH is performed.