RENAL HYPOURICEMIA - PREVENTION OF EXERCISE-INDUCED ACUTE-RENAL-FAILURE AND A REVIEW OF THE LITERATURE

Isolated renal hypouricemia from defective uric acid reabsorption and/ or secretion is a well-described entity, with a prevalence of 0.12% to 0.20% in Japan. It is rarely associated with exercise-induced acute r enal failure (ARF). The etiology of ARF is debated, Prevention of ARF in renal hypouricemia has not been previously addressed. A 29-year-old Pakistani man had recurrent exercise-induced ARF. He was found to hav e isolated renal hypouricemia: serum uric acid 0.5 mg/dL, 24-hour urin e uric acid 472 +/- 25 mg (+/-SD), and fractional excretion of uric ac id 55.2% to 69.4%. Both pyrazinamide and probenecid decreased fraction al excretion of uric acid and uric acid excretion rate (UVUrate) in ou r patient, suggesting either a partial presecretory and postsecretory reabsorption defect or increased secretion. We investigated renal uric acid excretion during exercise in our patient and four control subjec ts. All five subjects underwent a physical fitness test (PFT). Our pat ient developed ARF. Uric acid excretion rate increased in our patient, from 0.48 mg/min at baseline to 1.49 mg/min 4 hours after the PFT, as did the urine uric acid to urine creatinine ratio (U-UA/U-Cr) (0.29 t o 1.49). In the controls, UVUrate and U-UA/U-Cr were unchanged after t he PFT: UVUrate was 0.46 +/- 0.10 mg/min at baseline and 0.59 +/- 0.04 mg/min 4 hours after the PFT, while U-UA/U-Cr was 0.30 +/- 0.04 at ba seline and 0.36 +/- 0.04 at 4 hours. All five subjects took allopurino l 300 mg daily for 5 days and repeated the PFT. In our patient, allopu rinol prevented the ARF as well as the exercise-induced increases in U VUrate (0.28 mg/min to 0.22 mg/min) and U-UA/U-Cr (0.25 to 0.17). In t he controls, the UVUrate and U-UA/U-Cr responses to exercise were not altered. We conclude that increased renal excretion of uric acid durin g exercise was responsible for the ARF in our patient with renal hypou ricemia and that successful prophylaxis with allopurinol is possible. This is a US government work. There are no restrictions on its use.