Acute renal failure after exercise in a patient with renal hypouricemia

A 22-year-old man had recurrent exercise-induced acute renal failure (ARF). He was found to have isolated renal hypouricemia: serum uric acid level was 0.7-1.0 mg/dl and fractional excretion of uric acid (FE(UA)) was 37%-43%. He showed no suppression of FE(UA) following the the administration of pyrazinamide, and no increase of FE(UA) after benzbromarone, suggesting a subtotal defect. We investigated renal function, FE(UA), and serum nitric oxide after a treadmill exercise test in our patient and two control subjects. On the day after the exercise test, plain and enhanced abdominal computed tomography (CT) scans were performed in our patient. During the arterial phase, early equilibration phase, equilibration phase, and 2, 6, and 24h after the injection of contrast medium, renal CT scans were performed at the same slice level. Although ARF was not induced by this level of exercise, the CT scans showed patchy contrast enhancement 2, 6, and 24h after contrast medium administration. This finding suggests that patchy renal vasoconstriction may occur in patients with renal hypouricemia after strenuous exercise, even in the setting of normal creatinine clearance.