The delay of approximately a decade in the clinical expression of cardiovascular disease in women compared to men is believed to be a consequence of the antiatherogenic effect of estrogen prior to menopause. Indeed, surgical removal of the ovaries prior to natural menopause puts women at risk for premature cardiovascular disease unless treated with estrogen replacement therapy. Another big concern of women today as they reach menopause age is osteoporosis. At least 26 million American women are estimated to be at risk of bone fracture because of osteoporosis or low bone mineral density. Bone loss can occur for several years prior to menopause due to anovulation in the premenopausal years, but loss is rapid immediately after menopause, and then continues indefinitely.
Fractures usually occur first in the wrist, then in the spine, and finally in the hip.
Most researchers agree that estrogen replacement therapy should start soon after menopause and continue indefinitely. The estrogenic potency of Estradiol is 12 times that of estrone and 80 times that of estriol. For this reason estradiol is considered the major estrogen, although the estrogenic effects of estrone are far from negligible. There is an interconversion of estradiol to estrone and vice a versa. When estradiol is given orally it is converted to estrone by the liver.