Low dose adrenocorticotropin infusion in continuous ambulatory peritoneal dialysis patients

The adrenocorticoid responses to low doses of ACTH (0.03-10 ng/min) in sodium-deplete normal subjects and end-stage renal disease patients maintained on continuous ambulator peritoneal dialysis (CAPD) were compared. All subjects were pretreated with dexamethasone. ACTH was administered by graded iv infusions in doses of 0.03, 0.3, 1.0, 3.0, and 10 ng ACTH/min. Each rate of infusion was maintained for 30 min. Plasma aldosterone, 18-hydroxycorticosterone, corticosterone, 18-hydroxy-11-deoxycorticosterone, and cortisol were measured in plasma sampled at the end of each rate of infusion in both groups. Plasma 11-deoxycorticosterone was measured in CAPD patients. The plasma steroid levels in the CAPD patients after each infusion rate were equal to or greater than the levels in normal subjects. The slopes of the cumulative increases above baseline in plasma steroid levels in the CAPD patients were equal to or greater than those in the normal subjects. In both groups, plasma corticosterone increased the most and aldosterone the least. Kinetic analyses indicated that the adrenal responses to low dose ACTH were not linear. A distinct threshold for ACTH-stimulated increase in plasma adrenocorticoid levels, if present, is very low. The responses of plasma adrenocorticoids to low dose ACTH are normal in CAPD patients.