Estrogens in the prevention of osteoporosis in postmenopausal women.

Menopause-related bone loss leaves a woman at high risk for fractures. Estrogen use by postmenopausal women, especially when started within 3 years of the last menstrual period, prevents bone loss and reduces the risk of osteoporotic fractures. Estrogens do not restore lost bone. Withdrawal of estrogen therapy is followed by significant bone loss, thus suggesting that long-term therapy is needed. Concomitant progesterone therapy does not impair estrogen's bone-preserving activity.