Hormone-replacement therapy (HRT) is a physician-prescribed program of treatment for women who are experiencing hormonal imbalances, during or after the occurrence of menopause. It usually refers to supplementing the body with the hormones estrogen and progesterone, which naturally decline during menopause, to treat the symptoms that follow.
Estrogen is produced by the ovaries along with progesterone. Together, these two hormones regulate menstruation and ovulation. Menopause occurs as part of a woman’s natural aging process when production of these hormones becomes erratic and eventually stops. This may happen over several years. At the beginning, a woman experiences irregular menstrual periods, often accompanied by hot flashes, night sweats, and a lack of energy. Eventually, her menstrual periods stop completely. Long-term postmenopausal symptoms include pelvic organ atrophy, bone changes that range from joint aches to osteoporosis, and circulatory changes such as varicose veins or even high blood pressure. Sometimes, circulatory changes lead to heart disease or stroke.
HRT works by supplementing the body with estrogen or with a combination of estrogen and progesterone, relieving some of the menopausal symptoms. Other beneficial effects of HRT include promoting the amount of HDL (“good”) cholesterol and decreasing the amount of LDL (“bad”) cholesterol in the blood. HRT slows or stops the loss of bone mass and density (osteoporosis), and may even increase bone density.
HRT may be given in the form of either naturally derived or synthetically produced estrogen. Less potent forms of natural estrogen, termed phytoestrogens, are derived from plants and can also be used in HRT. The two most common regimens are cyclic HRT and continuous HRT. The cyclical regimen is designed to mimic the natural menstrual cycle, in which estrogen is taken every day and, for 2 weeks of the month, progesterone is taken also. In continuous HRT, estrogen is taken in
conjunction with a lower dose of progesterone every day. Transdermal estrogen patches, which are applied only one to two times per week, can also be used.
The risks associated with HRT include an increase in blood clots, heart attack, and abnormal mammograms when taken short-term. Risks of long-term HRT include an increased risk for breast cancer, heart disease, gallstones, pulmonary embolism, deep vein thrombosis, stroke, Alzheimer’s disease, and other dementias. Many of these findings were discovered as a result of the Women’s Health Initiative (WHI) study. The WHI is a major research program established by the National Institutes of Health (NIH) to address the most common causes of death, disability, and poor quality of life in postmenopausal women. The study included the assessment of the effects of treatment with estrogen plus progesterone, or estrogen alone, in healthy pos menopausal women. The estrogen-plus-progesterone study was prematurely halted in July 2002 when it was found that the risks (increased breast cancer, coronary heart disease, strokes, and pulmonary embolism) outweighed the benefits (fewer hip fractures and colon cancers). In March 2004, the estrogen-alone trial was also prematurely halted. The NIH reported that this therapy did not appear to affect the risk for heart disease, but increased the risk for stroke in postmenopausal women. This therapy also significantly increased the risk for deep vein thrombosis, had no significant effect on the risk for breast or colorectal cancer, and reduced the risk for hip and other fractures. Because the WHI studies focused on the risks of long-term use of HRT rather than shorter-term use, the NIH recommends that the information obtained should be used by women considering use of HRT for longer than 3 or 4 years. The decision to use HRT should be made after weighing risks and benefits and on the basis of the individual woman’s health history and specific needs.
- Jacobowitz, S. (Ed.). (1999). The estrogen answer book:150 Most-asked questions about hormone replacement therapy. Boston: Little, Brown.
- National Institutes of Health (NIH), http://www.nih.gov/ PHTindehtm
- Women’s Health Initiative (WHI), http://www.nhlbi.nih.gov/whi/