Long term evolution of glucocorticoid-suppressible hyperaldosteronism

It is generally held that idiopathic hyperaldosteronism and glucocorticoid-suppressible hyperaldosteronism (GSH) are distinct entities, distinguishable by thorough investigation. We report a patient who presented in 1974 at age 15 yr with blood pressure of 240/120 mm Hg, serum K of 3.1 mM, low renin, and high normal aldosterone excretion, with findings diagnostic of GSH. After dexamethasone treatment (2 mg/day for 4 weeks), urinary aldosterone was undetectable (less than 1 microgram/24 h), associated with correction of hypertension and hypokalaemia. While untreated, plasma aldosterone increased in response to ACTH infusion at a dose that did not influence plasma cortisol. Plasma aldosterone at 0800 h while recumbent was higher than in subsequent samples taken while ambulant, consistent with ACTH dependence of aldosterone secretion. Blood pressure, renin, and potassium remained normal for 4 yr during treatment with dexamethasone (0.5-0.75 mg/day), but hypertension then slowly returned. After 7 yr, the original studies were repeated. Urinary aldosterone excretion was again in the high normal range after 3 weeks of no treatment, but both plasma renin and aldosterone consistently increased in response to upright posture. After dexamethasone treatment (2 mg/day) for 4 weeks, urinary aldosterone was not suppressed (excretion rate, 10.8, 9.2, and 5.7 micrograms/day; urinary Na, greater than 100 mmol/day; urinary cortisol, less than 1 microgram/day). At this time, dexamethasone did not alleviate hypertension or increase renin. Control of blood pressure has been readily achieved, 8-12 yr after diagnosis, with a low dose of beta-adrenergic antagonist and amiloride. Aldosterone remains incompletely suppressible during sodium loading, so that the findings now resemble those of idiopathic hyperaldosteronism. This sequence indicates that glucocorticoids may not permanently control hypertension in GSH. The transient dominance of ACTH in control of aldosterone secretion indicates that the relationship between GSH and idiopathic hyperaldosteronism merits further evaluation in long term studies.