Prevention and treatment of osteoporosis with ovarian hormones.

A considerable body of evidence has now been assembled demonstrating loss of ovarian function is associated with increased skeletal remodeling and acceleration of bone loss. The available data suggest that this is probably the most significant risk factor of osteoporosis for most women. The presence of other risk factors may well magnify the effect of menopause either by reducing peak bone mass, enhancing rate of bone loss, or by increasing the risk of falls and injury in later life. Estrogen therapy reverses the increased remodeling and reduces the rate of bone loss significantly. Controlled studies have confirmed that this effect persists as long as estrogens are prescribed (at least 10 years) and ceases after therapy is stopped, when there is an acceleration of bone loss that is similar to that following oophorectomy. Consequently, the earlier estrogen therapy is begun, and the longer it is continued, the more effective are the results. The available data suggest that a minimum of 5-10 years treatment may be necessary to reduce the likelihood of hip fracture by about 50%, and vertebral fracture risk may be cut by as much as 90%. Certain progestogens may also inhibit bone loss, but their addition to estrogen in sequential or combination therapy does not appear to modify the effects of estrogen significantly.