Endocrine characterization of the adrenal adenomas in a case of primary aldosteronism

A 48-year-old man with typical clinical and biochemical features of primary aldosteronism was revealed on operation to have two adrenocortical adenomas in the left gland. An ACTH-dependent pattern of aldosterone secretion was demonstrated in terms of the parallel circadian rhythm of aldosterone with cortisol and the exaggerated response to ACTH but not to angiotensin II. Aldosterone and cyclic AMP release in vitro was studied using collagenase-dispersed cells of each adenoma. Not only the large adenoma but the small one showed basal and ACTH-stimulated releases of aldosterone greater than those by the adjacent tissue. In response to angiotensin II and potassium, the small adenoma showed a larger maximum increment of aldosterone than the large adenoma. This difference in endocrine features of the two adenomas suggests a possible transformation in their nature during development. An exaggerated cyclic AMP release by the adenomas in response to ACTH in vitro suggested the possible role of increased adenylate-cyclase activity in the hyperresponse of aldosterone to ACTH in this case.