Primary aldosteronism with normal aldosterone levels in blood and urine.

A 47 year old women examined for hypertension (200/100 mmHg) was normokalaemic, and had low plasma renin activity (PRA) (0.1 ng/ml X h) and normal aldosterone levels in both plasma (7-13 ng/dl) and urine (4.7-7.4 micrograms/day). Computed tomography (CT) and scintiscan indicated an adenoma on the right adrenal gland, which was then removed. The histology of the adenoma and analysis of the aldosterone content were compatible with the criteria for an aldosterone-producing adenoma. Three months after surgery, her hypertension had improved, serum potassium levels had increased slightly, and PRA had normalized. This was an unusual form of primary aldosteronism which showed normal levels of aldosterone in both blood and urine.