Effect of ACTH on renal excretion of purine bases in a patient with isolated ACTH deficiency.

We investigated the renal transport of purine bases (uric acid, hypoxanthine and xanthine) after rapid and continuous ACTH loading tests in a patient with isolated ACTH deficiency, a rare cause of secondary adrenocortical insufficiency. Plasma uric acid concentration and the urinary ratio of uric acid/creatinine did not change in the rapid ACTH test, which did not increase plasma cortisol concentration. In the continuous ACTH loading test, the plasma concentration of uric acid and oxypurines (hypoxanthine and xanthine) decreased, and the urinary excretion and fractional clearance of them increased as well as the plasma concentrations and urinary excretion of cortisol. These findings suggest that glucocorticoid directly affects the common renal transport pathway for uric acid, hypoxanthine, and xanthine.