This article is about the treatment with sex steroids. For hormone replacement therapy in general, and for other instances in which hormones might be prescribed, see hormone therapy.
Hormone replacement therapy (HRT) is a system of medical treatment for postmenopausal women, based on the assumption that it may prevent health problems caused by diminished circulating estrogen hormones. The treatment involves a series of drugs designed to artificially boost hormone levels. Estrogens and progestagens are the two main types of hormones involved. HRT is also used by transsexuals to aid them in attaining the secondary sex characteristics of their desired sex.
HRT provides low dosages of an estrogen and a progestagen. In women who have had a hysterectomy only an estrogen is given, unopposed estrogen therapy. HRT treatment is by tablets taken either cyclically (estrogen daily and progestagen from around two weeks every month; sequentially combined HRT or scHRT) or continuously (constant dosage of both types of hormones; continuous combined HRT or ccHRT). Sometimes also an androgen is added to treat reduced sexual desire (libido) after menopause.
It is seen as either a short-term relief (often one or two years, usually less than five) from menopausal symptoms (hot flashes, irregular menstruation, fat redistribution etc.) or as a longer term treatment to reduce the risk of osteopenia leading to osteoporosis.
There are certain potential risks associated with HRT. Oral estrogen intake can exacerbate existing liver or gallbladder problems and cause blood clots. Estrogens can also effect blood triglyceride levels and so may increase the risk of cardiovascular problems. Long term use of HRT may also increase the risk of breast cancer. Unopposed estrogen therapy in women with a uterus may also increase the risk of uterine cancers
Due to the potential problems of HRT a number of alternative therapies have been used. A mix of different drugs to control symptoms is one approach, as are certain changes to the diet and regular exercise. To combat the risk to bones dietary changes to increase calcium uptake, exercise, and drugs such as biphosphates, selective estrogen receptor modulators or calcitonin have been tried.
For male-to-female transsexuals, HRT includes antiandrogens in addition to the estrogens and progestagens mentioned above. For female-to-male transsexuals, HRT consists only of androgens.