Circulating hormone levels in menopausal women receiving different hormone replacement therapy regimens. A comparison

To measure and compare plasma levels of sex hormones after the administration of different hormone replacement therapy (HRT) regimens.

Ninety women with natural menopause were randomized into this comparative study. Eighty-five women completed one year of follow-up. Patients were randomly assigned to five groups. The first received 0.6 mg/d of conjugated equine estrogen (CEE) cyclically (n = 15). The second received 50 micrograms/d of transdermal estradiol (E2) cyclically (n = 17), and the third received 0.6 mg/d of CEE continuously (n = 17). All these groups also received 2.5 mg of medroxyprogesterone acetate (MPA) sequentially for the last 12 days of HRT, while the fourth therapy group received 0.625 mg/d of CEE and 2.5 mg/d of MPA continuously (n = 19). The fifth group constituted a treatment-free control group (n = 22). Levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), E2, estrone (E1), prolactin (PRL), testosterone (T), androstenedione (A4), dehydroepiandrosterone sulfate (DHEA-S) and sex hormone binding globulin (SHBG) were determined prior to HRT and during the last week of the 6th and 12th months of HRT, between days 21 and 24 of estrogen administration.

After HRT we found decreases in FSH, LH and PRL levels, increases in E2, E1 and SHBG, and no modifications in T, A4 and DHEA-S plasma levels. There were no significant differences between the treatment groups in FSH, LH, E2, PRL, T, A4 or DHEA-S. E1 and SHBG were significantly higher in the groups with oral HRT.

All the observed changes in hormone levels are to be expected after HRT except for the decrease in PRL levels. Finally, although MPA dosage was not the focus of the present study, our results suggest that the dosage of 2.5 mg/d of MPA in sequential regimens is clearly inadequate to protect the endometrium from hyperplastic changes.