Responsiveness of plasma aldosterone: dependency upon basal secretory activity

The responsiveness of plasma aldosterone levels to various stimuli was evaluated in 44 normal subjects, 17 patients with mild to moderate renal failure, 30 patients with terminal renal failure, and 13 anephric subjects. Plasma aldosterone, renin activity (PRA), cortisol, sodium, and potassium levels were measured before and after one hour of upright posture (N = 191); ACTH infusions (N = 76); and angiotensin II infusion (N = 36). Plasma aldosterone responses correlated (r greater than or equal to 0.53; p less than 0.02) with basal plasma aldosterone levels during upright posture in all four groups, with ACTH infusion in all groups except anephric subjects, and with angiotensin II administration in patients with mild to moderate renal failure or patients combined. These relationships were consistently closer than those between aldosterone responses and changes in PRA or basal PRA. However, postural aldosterone responsiveness at any given basal aldosterone level was significantly lower in patients with renal disease than in normal subjects, and this was associated with a parallel impairment in renin responsiveness. In contrast, when related to basal levels aldosterone responsiveness to ACTH or angiotensin II appreared to be comparable in normal subjects and patients with renal disease. Aldosterone responses to posture, ACTH, or angiotensin II did not correlate with associated changes in plasma cortisol, sodium, or potassium levels. These data suggest that basal adrenal secretory activity is a major factor conditioning aldosterone responsiveness to various stimuli in normal subjects as well as in patients with renal disease.