Selective hypoaldosteronism despite prolonged pre- and postoperative hyperreninemia in primary aldosteronism

In a prospective study of 7 patients with aldosterone-producing adenoma (APA), long-term (6-72 months) preoperative stimulation of plasma renin activity (PRA) by diuretic therapy (spironolactone plus hydrochlorothiazide) did not prevent selective aldosterone deficiency postoperatively. In all patients aldosterone excretion rate (AER) fell to subnormal values (from a mean of 97 to 2.6 mug/24 h) following removal of APA, although PRA remained elevated. Generalized adrenocortical insufficiency was excluded by the demonstration of normal baseline plasma cortisol and urinary 17-OHCS and the appropriate response to ACTH stimulation. In 6 of 7 patients studied 1-3 months postoperatively, short-term (4 days) sodium deprivation evoked normal increases in PRA, but AER response was blunted (except in 1). Restudy of 3 of 6 patients after 6-12 months revealed that aldosterone production had returned to normal. These results indicate that renin deficiency is not the principal cause of postoperative selective hypoaldosteronism in these patients. On the other hand, they appear to substantiate the possibility raised by in vitro and in vivo studies that spironolactone can directly inhibit aldosterone biosynthesis.