37 RENAL HANDLING OF HYPOXANTHINE AND XANTHINE IN NORMAL SUBJECTS AND IN CASES OF IDIOPATHIC RENAL HYPOURICEMIA

Abstract

Pyrazinamide(PZA) was used to study the renal handling of hypoxanthine, xanthine and uric acid in two normal subjects and in four patients with idiopathic renal hypouricemia. In normal subjects the suppression rate by PZA in the excretion of uric acid, hypoxanthine or xanthine is different for each compound. In a patient with postsecretory reabsorption defect, the ratio of uric acid clearance to creatinine clearance was reduced from 45.8 to 0.6% by PZA, the ratio of hypoxanthine clearance to creatinine clearance from 31.9 to 16.6% by PZA, and the urinary excretion of xanthine from 10.0 to 3.0 ug/min. PZA suppressed all the excretion of the three compounds. This effect is similar to in normal subjects. In three patients with presecretory reabsorption defects, PZA howed almost no suppressive effect on the ratio of uric acid clearance to creatinine clearance, the ratio of hypoxanthine clearance to creatinine clearance and the urinary excretion of xanthine. This similar suppressive or unchanged effect of PZA in response to both normal and morbid conditions suggests that the renal handling of hypoxanthine and xanthine, especially xanthine, is similar to that of uric acid.