Renal Handling of Uric Acid: Hypouricemia and Tubular Urate Secretion

To the Editor.

—In the November 1985 issue of theArchives, Shichiri et al¹reported on three patients with inappropriate secretion of antidiuretic hormone syndrome, and increased renal clearance of uric acid. In two patients, the fractional excretion of uric acid (Cur/Ccr) increased to 435% and 267%, with respect to mean baseline values in response to probenecid administration. They conclude that in both patients increased urate excretion is the result of enhanced tubular secretion of uric acid. This conclusion is based on the assumption of a four-component model for urate excretion. The authors were provided evidence for this model by Steele and Rieselbach.² Review of the literature shows that in 1967, these authors did not propose that reabsorption of secreted urate could modulate the amount of uric acid appearing in the final urine specimen. Evidence for a postsecretory reabsorptive mechanism of urate relates to the canceling effect of