Measurement of Aldosterone in Peripheral Blood of Man and Sheep¹

Abstract

A double isotope derivative dilution procedure is described for the measurement of aldosterone in peripheral blood of man and the sheep. 4-14C-aldosterone is used as the recovery indicator and 3H-acetic anhydride to form the radioactive derivative. The over-all nonspecific blank of the method for 76 samples was 0.22 ±0.003 mμg/20 ml when distilled water, or blood, or plasma from adrenalectomized castrated sheep or humans, was analyzed. Details of the specificity, accuracy and precision of the method are presented. The mean plasma aldosterone obtained from 25 normal recumbent humans, on a diet containing 80–120 mEq sodium/day, was 5.8 ±4.5 ±0.9 mμg/100 ml plasma. Sheep in normal sodium balance had levels below 1 mμg/100 ml blood. All values quoted have been corrected for blank. An enzymic hydrolysis procedure is described for the measurement of ring labeled tritiated steroids when 3H-acetic anhydride is used for derivative formation.