Normotensive primary aldosteronism: report of a case

A 23-yr-old male patient with normotensive primary aldosteronism is reported. He complained of muscle weakness, polydipsia, and polyuria. His blood pressure was generally 118/60 to 124/70 mm Hg. Serum sodium, potassium and chloride were 152.2.2, and 108 meq/liter, respectively. Arterial blood pH, glomerular filtration rate, renal plasma flow and circulating plasma and blood volumes were normal, and plasma bicarbonate was normal or elevated. PRA was 0.16 ng/ml.h and did not increase significantly after sodium deprivation, ambulation, and iv furosemide injection. Plasma aldosterone was 64.1 ng/100 ml. He showed pressor responses to infused angiotensin II and norepinephrine which were similar to those in normal men. Adrenal scintiscanning after iv injection of [131I]6 beta-iodomethyl-19-nor-cholesterol during dexamethasone administration showed dense uptake on the right adrenal and minimal uptake on the left. Intravenous infusion of angiotensin III at a rate of 20 ng/kg. min for 30 min did not cause an increase in plasma aldosterone. Serum electrolytes became normal after spironolactone but not after dexamethasone. At surgery, the right adrenal, bearing a benign adenoma, was removed. After surgery, blood pressure was unchanged, but all biochemical abnormalities disappeared. The cause of this normotension remains to be elucidated, but the diagnosis criteria of primary aldosteronism should now be partly modified.