RENAL FUNCTION IN GOUT .3. ESTIMATION OF TUBULAR SECRETION AND REABSORPTION OF URIC ACID BY USE OF PYRAZINAMIDE (PYRAZINOIC ACID)

Renal clearance was measured in ten patients with primary gout and five normal men before and after the administration of pyrazinamide or pyrazinoic acid to suppress tubular secretion of uric acid, thus permitting separate estimations of tubular influx and efflux of uric acid. In both gouty and nongouty subjects tubular reabsorption of the filtered urate was found to be virtually complete, the excreted uric acid deriving almost entirely from tubular secretion. No significant correlation could be made between plasma urate concentration and rate of tubular secretion of urate in normal persons in the steady state with Pur 3 to 7 mg. per cent, or in gouty subjects with Pur increased to about 9 mg. per cent; however, tubular secretion of urate was increased in gouty subjects with Pur > 9 mg. per cent (gouty overexcretors of uric acid). Allopurinol given to gouty subjects for short-term periods decreased the renal clearance of uric acid due to a disproportionate decline in tubular secretion of uric acid; conversely, feeding of RNA had the reverse effects, in both instances corresponding qualitatively and quantitatively to the changes in normal man similarly treated by Steele and Rieselbach. On the basis of the available evidence, it is concluded that the pattern of renal regulation of uric acid excretion in primary gout corresponds to that in normal man, and that it is not necessary to postulate a specific renal defect in elimination of uric acid. © 1969.