Effect of Alkalized Urine on Renal Calculi in Patients With Gout: a Protocol for a Randomized Controlled Trial

Abstract Background: The prevalence of renal calculi in patients with gout is high. Alkalized urine has been recommended by the 2020 European Association of Urology (EAU) guidelines to promote calculus dissolution. However, randomized controlled trials are lacking. Hence, it wasn't recommended by the 2020 American College of Rheumatology (ACR) guidelines. Objective: The present study aimed to determine the effect of sodium bicarbonate-alkalized urine on renal calculus in patients with gout. Methods: In this randomized, placebo-controlled, double-blinded trial, patients with gout combined with renal calculi are randomized (1:1) to the placebo and sodium bicarbonate groups. All patients were administered febuxostat (40 mg/day) and concomitant anti-inflammatory prophylaxis therapy. The 1–12-week group is double-blinded, and the 13–24-week group is open-labeled. The primary outcome is the rate of patients whose renal calculus volume is reduced after 12 weeks. The secondary outcomes included the volume changes of renal calculi, uric acid changes, the rate of patients with serum uric acid (sUA) levels < 360 μmol/L, the changes in estimated glomerular filtration rate (eGFR), the pH value of urine, and the adverse effects after 12 and 24 weeks.Discussion: This trial would evaluate the efficacy and safety of sodium bicarbonate-alkalized urine on renal calculi in patients with gout.Trial registration: ChiCTR, ChiCTR2100045183, Registered 7 April 2021http://www.chictr.org.cn/showproj.aspx?proj=124742