Plasma
estradiol concentrations were determined by radioimmunoassay in various endocrine disorders using antiserum to
estradiol-17beta succinyl
bovine serum albumin. Clinical significance and diagnostic value of plasma
estradiol were assessed in hypothalamic-pituitary, adrenal and
gonadal disorders. In general,
estradiol concentration was correlated well with the degree of sexual maturity and was of great diagnostic use. Plasma
estradiol in females mainly originated from the ovary, while the testis is the principal source of
estradiol in males. The adrenal gland seemed to play a minor role as a source of
estradiol at least in normal males and females. The role of
estradiol in
gynecomastia and in
liver disease was also investigated. More than a half of the cases with
gynecomastia had elevated concentrations of plasma
estradiol, which probably explains the pathogenesis of this manifestation. Cirrhotic patients showed frequently hyperestrogenemia probably due to delayed disappearance of
estradiol. In the study of stimulation with
human chorionic gonadotropin (HCG), 3,000 IU daily for three days in ten normal men, the peripheral concentrations of esradiol showed maximum and fourfold increases 24 hours after the 1st injection of HCG. The
testosterone levels, on the other hand, increased stepwise and reached a maximum of about two times preinjection levels 24 hours after the 3rd injection. In
gonadal disorders, HCG produced various patterns of plasma
estradiol and
testosterone in accordance with the gonadal conditions and dissociated response patterns of both
sex hormones were frequently found. The determination of plasma
estradiol was useful in the study of the function of not only the ovary, but also the testis and the simultaneous measurement of plasma
estradiol and
testosterone after HCG administration presented interesting informations about pathophysiology of
gonadal disorders.