Gonadotropin dynamics in women receiving immediate or delayed transdermal estradiol after oophorectomy

A prospective study was performed in 24 premenopausal women to evaluate the gonadotropin dynamics of pharmacologic doses of transdermal estradiol-17 beta (E2) administered after bilateral oophorectomy. Patients were given 0.2-mg transdermal E2 patches for 2 weeks, followed by 0.1-mg patches for 4 weeks either immediately postoperatively (immediate estrogen replacement therapy [ERT]) or beginning 12-14 days after surgery (delayed ERT). Serum gonadotropins and E2 levels were measured serially, and postmenopausal symptoms were prospectively recorded. Administration of 0.2 mg transdermal E2 immediately after surgery suppressed the post-castration rise in gonadotropins for at least 4 days, but LH and FSH levels did increase to the menopausal range after 2 weeks despite continued therapy. Sustained circulating levels of E2 with transdermal E2 therapy were comparable to follicular phase values. Vasomotor symptoms were well controlled by 0.2 mg of transdermal E2 in the majority of patients during the clinical trial. There was no significant estrogen-related morbidity despite the large doses used. Two patients had skin irritation at the patch site causing discontinuation of therapy. These data suggest that large doses of transdermal E2 can suppress gonadotropin levels only for a brief interval. We were unable to demonstrate any long-term alteration in the hypothalamic-pituitary set point for sensitivity to exogenous E2.