Normotensive primary aldosteronism.

A very unusual case of normotensive primary aldosteronism is described. A 25 year old woman first noticed numbness of both hands followed by a typical tetany attack. The blood pressure was within normal ranges. The results of other physical examinations were negative except for the findings of Trousseau's sign. Hypokalemi, increased potassium clearance, disturbed urine concentration and increased circulating plasma volume were noticeable. Diagnosis was established by (1) increased levels of plasma aldosterone, (2) low plasma renin activity, (3) normal adrenocortical function and (4) typical aldosterone-producing adenoma. After removal of the adenoma, the abnormalities subsided. The lack of hypertension in primary aldosteronism is a rare condition. Several possible causes of normotension must be considered, such as the early phase of primary aldosteronism, essential hypotension associated with primary aldosteronism and lack of concomitant secretion of other mineralocorticoids from the adenoma, but these were all negligible. As blood pressure response to the administration of angiotensin II was lower than is typical for primary aldosteronism, and the patient transiently suffered from frequent attacks of blackouts soon after the operation, the cause of normotension was thought to be due to the existence of a hypotensive mechanism which counteracts the increase in blood pressure in primary aldosteronism.