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Women's Health Initiative
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What are the effects of estrogen and menopause on bone health in women?
Estrogen is a hormone produced by the ovaries, and in small quantities by other body tissues. Estrogen plays a critical role in building and maintaining bone in adolescent and younger women. Throughout a person's lifetime, old bone is removed and new bone is added to the skeleton. In childhood and adolescence, new bone is added faster than old bone is removed, and the bones become larger, heavier, and denser. Women usually reach their maximum amount of bone, known as peak bone mass, between the ages of 20 and 30. After that, bone mass may remain stable or decline gradually, depending on a variety of lifestyle factors. Calcium and vitamin D and physical activity are also important for building bone and maintaining bone throughout life.
The reduction in estrogen production during menopause is the major cause of bone loss in women during later life. In the few years before menopause (defined as the completion of a full year without a menstrual period), the amount of estrogen produced by the ovaries starts to drop, resulting in a loss of bone mass. During menopause, the rate of bone loss increases as the amount of estrogen produced by the ovaries drops dramatically. Estrogen levels in postmenopausal women are about one-tenth the levels in pre-menopausal women. Bone loss is most rapid in the first few years after menopause but continues into the postmenopausal years.
Loss of bone mass due to low estrogen levels can also occur after a woman has had surgery to remove both her ovaries. This is sometimes called "surgical menopause." Surgical menopause can also result from failure of the ovaries following a hysterectomy, or following cancer therapy, such as chemotherapy or radiation treatments. Bone loss due to either natural or surgical menopause can lead to osteoporosis. But bone loss after menopause and with aging is natural and tolerable in many women and does not need to be treated unless the bone loss is so great that it leaves the bones fragile and prone to fracture.
What is the Women's Health Initiative?
