What is uric acid concentration in urine in patients with uric acid kidney stones? - a case study.

This case report describes a patient with uric acid kidney stones. Alkalization therapy using mainly potassium citrate is the first-choice treatment. When hyperuricosuria > 4 mmol/24 hours is present, xanthine oxidase inhibitors are added. It implies that accurate urine uric acid measurement is of high importance. Uric acid was measured in a 24-hour collection and a second-morning sample. Urine uric acid was measured after sample alkalization to pH > 6.5 and heating to 56 °C for 10 minutes, and for educational reasons without sample treatment. The uric acid excretion in the sample without alkalization in the 24-hour collection was 2.436 mmol, after alkalization, the excretion was 4.650 mmol/24 hours. Sample alkalization led to a prescription for xanthine oxidase inhibitor medication that is indicated as the second-line therapy when hyperuricosuria > 4 mmol/24 hours is present. This case study shows how the correct preanalytical phase is essential for medical decision-making.