Revisiting Uric Acid Stone Dissolution Kinetics: Insights for Optimizing Medical Therapy

Area of Science:

• Nephrology
• Urology
• Biochemistry

Background:

• Urine alkalinization is the primary medical therapy for uric acid (UA) stone dissolution.
• Existing recommendations are based on limited in vitro data and expert opinions.
• The impact of lowering urine UA concentration in patients without hyperuricosuria requires further investigation.

Purpose of the Study:

• To determine the optimal urine pH target for uric acid (UA) stone dissolution.
• To evaluate the effect of reducing urine UA concentration on UA stone dissolution kinetics.
• To refine medical therapy for patients with UA nephrolithiasis.

Main Methods:

• Utilized ultraviolet-visible spectrophotometry to analyze UA stone dissolution rates.
• Investigated dissolution kinetics in artificial urine across various pH levels and UA concentrations.
• Employed X-ray diffraction to examine crystal structures of precipitates.

Main Results:

• UA stone dissolution rates increased significantly with pH, with optimal dissolution at pH 7-7.2.
• Dissolution rates were significantly higher for grounded stones compared to intact stones.
• Lowering urine UA concentration enhanced dissolution only at pH >6.5 and after a 55% reduction.

Conclusions:

• Urine alkalinization is crucial for UA stone dissolution, with optimal results at pH 7-7.2.
• Increasing stone surface area (fragmentation) can further enhance dissolution.
• Adequate alkalinization is necessary for effective treatment, even with medications like allopurinol.