Evidence for the Presence in Human Plasma of an Estrogen-Binding Factor Other than Albumin: Abnormal Binding of Estradiol in Men with Hepatic Cirrhosis1

The binding of estradiol in diluted plasma of normal men, normal women and male patients with cirrhosis of the liver was determined under conditions of equilibrium dialysis at 4 C. Under these conditions the percentage of free estradiol in the plasma of the men was greater than that in the plasma of both the women and the cirrhotic subjects. The normal subjects had normal concentrations of albumin in their plasma, whereas the cirrhotic subjects had a lower concentration of albumin. The observed differences in the binding of estradiol cannot be correlated with these differences in albumin concentration; consequently, the existence of an additional estrogen-binding factor in plasma is postulated.