Title: HYPOURICEMIA DUE TO RENAL URATE WASTING: DIFFERENT TYPES OF TUBULAR TRANSPORT DEFECTS: 94
Abstract: Intrarenal handling of uric acid was evaluated in five patients with diminished serum urate levels (1.4 to 2.0 mg/dl) and increased renal clearance of uric acid (22.9 to 65.3 ml/min/1.73 m2). One patient with kappa light-chain disease and Fanconi syndrome showed a blunted uric acid excretion response to both pyrazinamide and probenecid, indicating a defective tubular reabsorption of urate. Three patients had recurrent calcium oxalate nephrolithiasis and one infant bening idiopathic hematuria. In addition to hyperuricosuria the infant and two patients with recurrent urolithiasis showed renal hypercalciuria. All evidenced normal responses to pyrazinamide. Compared to normal subjects, three patients showed a diminished and one an increased uricosuric response to probenecid. The former were considered to have a defective tubular urate postsecretory reabsorption and the latter an enhanced tubular secretion of urate. These results indicate that (1) hypouricemia may provide an important clue for the existence of an underlying disease, and (2) tubular urate transport defects may be of pathogenic importance in patients with recurrent calcium nephrolithiasis.