Determination of the Secretion Rate of Aldosterone in Normal Man by Use of 7-H3-d-Aldosterone and Acid Hydrolysis of Urine*

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Abstract
A method for measurement of the secretion rate of aldosterone is described. Urine is collected for 24 hours after injection of 1 μC (0.05 μg) of 7-H3-d-aldosterone. Aldosterone, extracted after acidification to pH 1, is purified. The specific activity of aldosterone diacetate is measured by fluorometry and counting of radioactive fractions appearing from the final partition column. In 10 normal subjects taking ordinary diets, the secretion rate of aldosterone ranged between 40 and 180 μg per 24 hours (mean, 109 μg). Higher values were obtained in a patient with hypertension and hypokalemia due to adrenal adenoma, in a patient with cirrhosis of the liver, and in 2 patients with idiopathic edema (diminished intake of sodium). Approximately 10% of the secreted aldosterone was excreted in the urine of normal subjects as a metabolite which releases free aldosterone at pH 1. The labeled aldosterone actually recovered after the first chromatogram averaged just above 6% of the injected dose, amounting to 3 to 12 μg of aldosterone per day. This value is in reasonable agreement with previously reported estimates.