The effect of estrogen treatment on plasma concentrations of steroid hormones, gonadotropins, prolactin and sex hormone-binding globulin in post-menopausal women.

Twenty-one post-menopausal women on no other medication were treated with a low dose (0.625 mg/day) of conjugated equine estrogen (CEE) for a mean (+/- SEM) period of 2.6 +/- 0.2 mth (range 1.75-4.75). Blood samples were collected before and at the completion of therapy, and alterations in the levels of prolactin (PRL), follicle-stimulating hormone (FSH), luteinizing hormone (LH), sex hormone-binding globulin (SHBG) and certain steroid hormones, including the free testosterone (T) index (T/SHBG) were studied. Following treatment, a significant increase in SHBG levels produced a significant decrease in the free T index (P less than 0.005). As expected, no changes were observed in the levels of PRL and steroid hormones other than estrone (E1) and estradiol-17-beta (E2). Our observations indicate that treatment of post-menopausal women with low-dose estrogen lowers the unbound T.