Hormone replacement therapy (HRT), also called hormone treatment (HT), restores a woman’s supply of the sex hormones estrogen and progesterone after her ovaries stop producing them. Production of these hormones declines as women age, then stops at menopause, the time that menstrual periods end.
Falling estrogen levels may cause symptoms as women approach menopause. For example, many women experience episodes of intense heat and sweating called hot flashes. When they occur at night, these episodes are called night sweats. These attacks may cause discomfort or disrupt sleep. Declining estrogen may also cause dryness and irritation of the vagina.
HRT relieves symptoms of menopause by restoring the body’s supply of estrogen. However, taking estrogen by itself increases the risk that a woman will develop cancer of the uterus, the organ in which a baby develops. To reduce this risk, doctors prescribe estrogen with progesterone for women who have a uterus. If the woman’s uterus has been removed, doctors usually prescribe estrogen alone. To relieve symptoms of menopause, HRT is usually needed for only a few months to a few years. The therapy may be risky for women with certain conditions, such as breast cancer, a tendency to develop blood clots, or liver disease, or for women who are at high risk for heart attack.
For many years, physicians thought that long-term HRT could prevent several diseases common in older women, such as heart disease, Alzheimer’s disease, and osteoporosis, a gradual loss of bone tissue that makes bones likely to break. HRT for disease prevention was often prescribed for many years or even for life.
In 2002, however, a study by the United States National Institutes of Health (NIH) showed that extended use of HRT using both estrogen and progesterone was not effective in preventing disease. Instead, the study found HRT actually increased the risk of heart disease, stroke, breast cancer, and blood clots. The study did find that women taking HRT have a lower rate of osteoporosis and colon cancer. However, the study showed that, overall, HRT caused more disease than it prevented. The NIH therefore advised physicians not to prescribe HRT to women for the sole purpose of preventing disease. Medical experts still recommend HRT for treating symptoms related to menopause but suggest that physicians limit the therapy to the shortest term possible.
Scientists have created artificial hormones that act like estrogen in some tissues but block estrogen’s effects in others. These hormones, called selective estrogen receptor modulators (SERM’s), may offer an alternative to HRT for some women. Raloxifene, one of the first such hormones developed, works like estrogen to reduce bone loss in osteoporosis. It also lowers levels of blood cholesterol, which may help protect against heart disease. Unlike estrogen, it does not stimulate tissues in the breast and uterus, which may cause disease, but it also does not prevent hot flashes.
See also Estrogen ; Flavonoid ; Menopause ; Progesterone .
