[A case of idiopathic hyperaldosteronism with normal plasma aldosterone concentrations for 5 years after onset: a...

We report a 54-year old man diagnosed as idiopathic hyperaldosteronism (IHA) at least 12 years after the onset. At the age of 42, he showed hypertension (162/100mmHg), hypokalemia, metabolic alkalosis, low plasma renin activity (PRA) and normal plasma aldosterone concentration (PAC) in a supine posture. Both PRA and PAC were elevated after a 2-hour ambulation following furosemide (60mg) injection. Since the accumulation of radioactivity following 131I-aldosterol injection with combined administration of dexamethasone was equally detected in both adrenal areas, he was diagnosed as low-renin essential hypertension (LREH). Blood pressure (BP) decreased to the normal range after treatment with nifedipine (40mg/day). At the age of 47, however, BP was hypertensive (164/106mmHg) serum potassium (K) level was normal. Although PAC was normal in a supine posture, it increased after a 2-hour ambulation following furosemide (60mg) injection. PRA after the stimulation was still suppressed despite the increase in PAC. At the age of 54, BP was 172/94mmHg. Serum K level was 3.4mEq/L. PRA was suppressed below 0.1 ng/ml/hr, while PAC was above the normal range (170pg/ml) in a supine posture. Serum cortisol and urinary excretion of 17-OHCS and 17-KS were within normal limits. PRA was still suppressed below 0.1 ng/ml/hr after a 2-hour ambulation following furosemide (60mg) injection, but PAC was markedly increased (330pg/ml). There was a diurnal rhythm of aldosterone, which was parallel to that of ACTH.(ABSTRACT TRUNCATED AT 250 WORDS)