MINERALOCORTICOID PRODUCTION OF ADRENAL-CORTICAL ADENOMAS

We studied in vitro and in vivo corticosteroid production as well as t he presence of symptoms of an increased mineralocorticoid effect in pa tients with 'silent' adrenal cortical adenomas, and compared these res ults to those found in patients with classical mineralocorticoid exces s syndromes. We found that under in vitro conditions, cells from 'sile nt' adrenal cortical adenomas (n = 19) produced substantial amounts of both zona glomerulosa and fasciculata steroids, although the producti on of steroids in these cells was lower compared to that in mineraloco rticoid-producing adenoma cells (n = 26). Patients with aldosterone-pr oducing and 'silent' adenomas had significantly increased plasma atria l natriuretic peptide levels, which remained non-suppressible after up right posture and furosemide administration. Of the 25 patients with ' silent' adenomas, 11 had low and non-stimulable plasma renin activity (PRA) before but, in most cases, not after adrenal surgery. When compa red to those with normal PRA (n = 14), patients with low PRA 'silent' adenomas (n = 11) had higher blood pressure which was significantly re duced after surgery, and a mild hypokalemia before but not after surge ry. Although basal plasma concentrations of aldosterone, 18-hydroxy-co rticosterone, corticosterone, deoxycorticosterone, 18-hydroxy-DOC, cor tisol, 11-deoxycortisol and 17-hydroxy-progesterone (17-OH-P) were not increased in either groups of 'silent' adenomas, ACTH stimulation pro duced a hyperreactive response for all measured steroids, of which an extremely high 17-OH-P seemed to be one of the most intriguing finding s. We consider that these observations in 'silent' adrenal cortical ad enomas may justify surgical intervention, irrespective of the size and potential malignancy of these adenomas.