Long-term postmenopausal hormone replacement therapy effects on bone mass: differences between surgical and spontaneous patients

Background: Hormone Replacement Therapy (HRT) begun soon after spontaneous menopause or oophorectomy minimizes or even reverses the loss of bone that occurs normally during those years. The persistence of this HRT protective effect at long-term on bone density, however, is not well documented. Aim: to evaluate the effects of 5 years of HRT in postmenopausal women on bone mineral density of the lumbar spine. Subjects and Methods: The 5-year prospective study enrolled 154 postmenopausal women, of them 136 completed the first year and were considered electible to continue the follow-up. These 136 postmenopausal women were allocated to two groups according their origin: surgical (n = 68) and spontaneous (n = 68). HRT was prescribed and bone mineral density (BMD) was measured at the lumbar spine prior to commencement of therapy, and then yearly for the duration of the study. All patients received a continuous therapy with standard dose (0.625 mg/day) of conjugated equine estrogen (CEE) or 50 mu g/day of 17-beta-Estradiol in transdermal therapeutic systems (TTS). Subjects who experienced natural menopause also received 5 mg/day of medroxyprogesterone acetate sequentially added to the last 12 days of estrogen therapy. Treated groups were compared with two non-treated control groups (surgical n = 77; spontaneous n = 53). Results: Our data showed that HRT increased the BMD of women who had experienced spontaneous menopause. Comparison with a control group revealed that HRT also protected against bone loss in women who had undergone surgical menopause. Conclusion: Long term hormone replacement therapy increases bone mineral density in women who have experienced natural menopause, and protects against bone loss in surgically postmenopausal women. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.