A Screening Test to Identify Aldosterone-Producing Adenoma by Measuring Plasma Renin Activity

• In an attempt to devise a screening test for aldosterone-producing adenoma (APA) among hypertensive patients, the serum sodium and potassium levels, plasma renin activity (PRA), plasma aldosterone concentration, and aldosterone-PRA ratio were measured in 348 patients with hypertension. Nine patients with a substantially elevated aldosterone-PRA ratio were selected and hospitalized for further investigations. All nine patients were then recognized by scintigraphy with labeled cholesterol, venography, and surgical excision as having APA. The serum concentration of potassium was subnormal in three of nine patients with APA. In patients with APA, administration of diuretics and salt restriction significantly elevated PRA. However, even under notable diurnal and day-to-day variations of plasma aldosterone concentrations, the aldosterone-PRA ratio was always elevated inappropriately (more than 400) in patients with APA. In contrast, after administration of diuretics, both the PRA and aldosterone levels increased significantly in patients with essential hypertension, but the aldosterone-PRA ratio was less than 200. Since the renin-angiotensin system seems to be a major factor controlling aldosterone secretion in normal subjects, it is suggested that an elevation of aldosterone-PRA ratio more than 400 is a useful screening tool for the prediction of APA among hypertensive patients. (Arch Intern Med1981;141:1589-1593)