The Nature of Circulating Estrogen.

Abstract

Summary The total estrogen content of blood and sera obtained from normal, pregnant and gonadotrophin-injected animals and women was uniformly low. Values approximating 0.5 μg of alpha-estradiol equivalents per 100 cc of blood were found. Two-thirds of the total estrogen was closely associated with the protein fraction. The remaining one-third existed mainly in a hydrophilic, non-protein conjugated form. Blood estrogens, as well as pure solutions of the sodium salts of estrone, alpha- and beta-estradiol, and estriol, were shown to dialyze quantitatively past a collodion membrane.