Renal tubular hypouricemia: evidence for defect of both secretion and reabsorption.

Two patients had hypouricemia due to increased uric acid clearance. They showed no decrease of urate clearance to creatinine clearance ratio (Cua/Ccr) following pyrazinamide administration, and no increase of Cua/Ccr after probenecid. One patient showed a limited decline in Cua/Ccr after intravenous furosemide. In the other patient, neither acetylsalicylate nor furosemide produced any noticeable change in Cua/Ccr. Both showed a normal diuretic response after intravenous furosemide. The results indicate that they had massive defects in urate transport along the nephron, probably including both secretion and reabsorption.