Estrogen replacement therapy after the menopause. Estrogenicity and metabolic effects

Certain metabolic effects were investigated in post-menopausal women undergoing oral estrogen replacement therapy for 6 months using various substances. The increases in serum concentration of the estrogen-sensitive proteins, pregnancy zone protein (PZP), and sex hormone binding globulin (SHBG) had very similar and dose-dependent patterns. Ethinyl-estradiol was found to be much more potent than the "natural" estrogens. Estriol in various doses did not increase the protein level. Gonadotropin inhibition occurred in a dose-dependent manner. In terms of FSH suppression ethinyl-estradiol was approximately 120 times as potent as the "natural" estrogens. There was a striking resemblance between the "estrogenicity" of four different estrogens when expressed both in inhibition of gonadotropins and in induction of the two serum proteins SHBG and ceruloplasmin. Estriol caused a significant depression of FSH when given orally in a dose of 2 mg three times daily. Prolactin was found to decrease during treatment with low doses of estrogens. Estrogen therapy was found to have only moderate effects on adrenal androgens. Tamoxifen, and anti-estrogen, was found to exert distinctly estrogenic effects during treatment of post-menopausal women. In post-menopausal women with low amounts of circulating estrogens the tamoxifen-receptor complex itself may produce a net estrogenic response. Serum samples from post-menopausal women treated with ethinyl estradiol 0.05 mg and estrone sulphate 2.5 mg daily were found to reduce the lymphocyte reactivity in mixed lymphocyte cultures.