Acute Renal Failure After Exercise in a Japanese Sumo Wrestler With Renal Hypouricemia

Familial renal hypouricemia is a hereditary disease characterized by extraordinary high renal uric acid clearance and is associated with acute renal failure (ARF). An 18-year-old sumo wrestler developed ARF after anaerobic exercise. Several hours after the exercise, he had a pain in the loins with oliguria, headache, and nausea. On admission, his serum uric acid was decreased despite the elevation of serum creatinine (9.5mg/dL). The level of creatine kinase was normal and there was no myoglobinuria or urolithiasis. Magnetic resonance imaging showed no significant abnormality. Renal function improved completely within 2 weeks of hydration treatment. After remission, hypouricemia became obvious (1.0mg/dL) from the initial level of uric acid (6.1mg/dL) and fractional excretion of uric acid was 49%. Polymerase chain reaction of a urate anion exchanger known to regulate blood urate level (SLC22A12 gene: URAT1) demonstrated that homozygous mutations in exon 4 (W258X). Both parents showed heterozygous mutation of the URAT1 gene, but both siblings showed no mutation. Thus, we describe a Japanese sumo wrestler of familial renal hypouricemia complicated with anaerobic exercise-induced ARF, with definite demonstration of genetic abnormality in the responsible gene, URAT1.