Health Encyclopedia

Hormone therapy

Definition

Hormone therapy is medication containing one or more female hormones, commonly estrogen plus progestin (synthetic progesterone). Some women, usually those who have had their uterus removed, receive estrogen-only therapy.

It is most often used to treat symptoms of menopause, such as hot flashes, vaginal dryness, mood swings, sleep disorders, and decreased sexual desire. Hormone therapy comes as a pill, patch, or vaginal cream.

Alternative Names

Hormone replacement therapy; HRT; Estrogen replacement therapy; ERT

Information

Based on early studies, many health care providers used to believe that hormone therapy might help reduce the risk of heart disease and bone fractures caused by osteoporosis, in addition to treating menopausal symptoms.

Over the last decade, several major studies evaluated the health benefits and the risks of hormone replacement therapy, including the risk of developing breast cancer, heart attacks, strokes, and blood clots. Evidence from these studies raised concerns for an increased risk for stroke, heart disease, breast cancer, and blood clots, depending on several factors that include the types of hormones used.

The information below includes detailed information from these studies.

ALZHEIMER'S DISEASE

Studies have not shown that hormone therapy slows down the symptoms of Alzheimer's disease. Other research is ongoing to determine whether hormone therapy benefits memory loss.

BLOOD CLOTS/THROMBOEMBOLIC DISEASE

The increased risk of blood clots from taking estrogen has been recognized for years. Generally, this risk has been associated with the use of birth control pills that contain high doses of estrogen. The risk is even higher if you smoke.

One study confirmed an increase in the number of blood clots in women taking estrogen or progestin. A more recent study indicates that this risk for blood clots is lower when estrogen is given through a patch instead of as a pill.

BREAST CANCER

One of the studies involving women taking estrogen and progestin was stopped early. The study found an increased risk of breast cancer in women taking hormone therapy for more than 3 - 5 years. The second part of the study looked at estrogen alone in women who no longer have a uterus. It did not find any increased risk of breast cancer in those women.

COLON CANCER

One study found that women who took estrogen or progestin have a lower risk of colon cancer than women not have not taken hormone therapy. Further study is needed.

DEPRESSION

Studies have shown that women who suffer from common vasomotor symptoms of menopause, mood swings, and sleep problems benefit from hormone therapy in the overall quality of their life. However, there is no scientific evidence that hormone therapy helps treat major depression.

GALLBLADDER DISEASE

Several studies have shown that women who use estrogen or progestin therapy have a higher risk of developing gallstones.

HEART DISEASE

Estrogen helps lower bad cholesterol (low density lipoprotein, or LDL) and raise good cholesterol (high density lipoprotein, or HDL). Lower levels of LDL and higher levels of HDL are associated with a decreased risk of heart disease. Researchers theorized that, by changing these levels, hormone therapy should lower risk of heart disease. Studies, however, did not show that estrogen helps reduce the risk for heart disease.

The number of heart attacks increased among women taking estrogen and progestin.

The biggest risk for heart disease may be for women who start hormone therapy long after menopause has begun. Women should not take hormone therapy strictly to prevent high cholesterol or heart disease. Lifestyle changes, including a healthy diet, regular exercise, and quitting smoking, and medications to lower cholesterol and control blood pressure are recommended for those conditions.

MENOPAUSE SYMPTOMS

During menopause, the amount of estrogen produced by a woman's ovaries drops. These naturally occurring low estrogen levels may cause symptoms that include hot flashes, sleep problems, mood swings, vaginal dryness, and pain with intercourse.

Most women see relief from the hot flashes, sleep difficulties, and vaginal dryness within a few weeks of taking hormone therapy. Short-term use (2 - 4 years) of the lowest possible dose of hormone therapy to treat symptoms of menopause still appears to be safe at this time. Usually, hot flashes and night sweats are less severe after a couple of years -- especially if hormone therapy is slowly reduced.

OSTEOPOROSIS

A woman's body produces less estrogen during and after menopause, which may affect her bone strength. One study showed that women taking hormone therapy had 35% fewer hip fractures and 29% fewer fractures than women not receiving hormones.

However, the short-term use of hormone therapy to relieve symptoms at the time of menopause does little to prevent fractures in women when they reach 75 - 80 years of age. Women who take estrogen to maintain bone density must continue taking estrogen because the beneficial effects on bones disappear when they stop taking it.

Estrogens are still used to prevent osteoporosis, but they are not approved to treat a woman who has already been diagnosed with the condition. Sometimes, if estrogen has helped a woman, and she cannot take other options for preventing or treating osteoporosis, the doctor may recommend she continue using hormone therapy. If you are considering taking hormone therapy to prevent osteoporosis, discuss the risks with your doctor.

See also: Osteoporosis.

OVARIAN CANCER

Some studies have found a small increased risk of ovarian cancer in women who took estrogen only (no progesterone) therapy. It is not clear if there is any risk for women who take both estrogen and progesterone. This risk is also a concern for women with previous endometriosis who then take estrogen alone.

STROKES

Studies have shown that hormone replacement therapy does not reduce the risk of stroke, and may increase the risk of stroke.

UTERINE CANCER/ENDOMETRIAL CANCER

Taking estrogen alone causes the lining of the uterus to grow. The risk for endometrial cancer is six to eight times higher in women who take estrogen alone, compared with those who do not.

Progestin (a synthetic progesterone) decreases the lining of the uterus. For women who still have their uterus, most doctors prescribe progestin to reduce the risk of endometrial cancer.

One study did not find any difference in endometrial cancer rates between the women who took hormones and those who did not. Depending on the form of hormone therapy, taking progestin may cause bleeding similar to a period. This combination of estrogen and progesterone may be in the form of one pill, or it may be two separate pills. It is also available in a patch.

URINARY INCONTINENCE

Hormone therapy has not been found to improve or reduce the incidence of incontinence after menopause.

SIDE EFFECTS OF HORMONE THERAPY

As with all medicines, side effects are associated with hormone therapy. Some women taking hormone therapy may have water retention, bloating, nausea, breast soreness, mood swings, and headaches. Changing the dose or form of hormone therapy may help reduce these side effects.

Some women have irregular bleeding when they start taking hormone therapy. Changing the dose often eliminates this side effect.

SUMMARY OF RISKS/BENEFITS

One study, called the Women’s Health Initiative, showed relatively small absolute increases in the risk of heart disease, breast cancer, blood clots, and stroke to an individual woman. However, when the entire population of postmenopausal women and the number of years a woman may be on hormone therapy are considered, the number of strokes, heart attacks, breast cancer cases, and blood clots appears to outweigh the protective effect of hormone therapy on bones. The results of this study are still being evaluated to look at the effects of hormone therapy on different subgroups of women, and more studies are underway to look at other types of hormone therapy.

Some women may still wish to consider hormone therapy for short-term treatment of menopausal symptoms. The key is to weigh the risks associated with taking hormone therapy against a particular woman's risk of heart disease or osteoporosis without taking hormone therapy. Other factors to consider include:

A woman's age
The age she became menopausal
The dose of hormone therapy being considered
Prior hormone replacement therapy taken in the past
Quality of life issues

Every woman is different. Your doctor should be aware of your entire medical history when considering prescribing hormone therapy.

FORMS OF HORMONE THERAPY

Hormone therapy is available in various forms, including pills, patches, and vaginal products. Your health care provider will start you on a regimen that is best suited for you. It may be necessary to try more than one regimen before finding the one that works best for you.

Cyclic hormone therapy is often recommended when a woman is starting menopause. With this therapy, estrogen is taken in pill or patch form for 25 days, with progestin added somewhere between days 10 - 14. The estrogen and progestin are used together for the remainder of the 25 days. Then, no hormones are taken for 3 - 5 days. There may be monthly bleeding with cyclic therapy.
Continuous, combined therapy is where estrogen and progestin are taken together every day. When this therapy is started, or when switching from cyclic to continuous therapy, women may have irregular bleeding. Most women stop bleeding within 1 year after starting this therapy.
A hormone therapy patch can be applied to the abdomen or the thigh. The patch allows the estrogen to be absorbed through the skin into the bloodstream. Some women prefer this method because they do not have to take pills. A woman using a patch may also have a lower risk of blood clots.
Vaginal cream containing estrogen may be given to women for vaginal dryness. Estrogen can also be given vaginally in tablet form or in a ring that slowly releases hormone therapy directly into the vagina. Estrogen delivered directly to the vagina may not relieve many of the other symptoms and does not appear to protect against bone loss. It is sometimes used alone to treat vaginal symptoms while not exposing the rest of the body to higher doses of the hormone. It may also be added to hormone therapy given by mouth or patch.

Additional medications may be recommended for some women with severe symptoms from menopause, or women who are at very high risk for osteoporosis or heart disease. One of these supplemental drugs might be androgen, a male hormone given with estrogen to relieve severe hot flashes. Nonhormonal medications are sometimes used either in addition to, or instead of, hormone therapy.

HEALTHY LIFESTYLE

In addition to hormone therapy, a women can take other steps to adjust to the changes in life during menopause. Eating healthy foods and getting regular exercise will also help decrease bone loss and maintain healthy heart muscle.

CALLING YOUR HEALTH CARE PROVIDER

It is important to have regular checkups with your health care provider when taking hormone therapy. If you have vaginal bleeding during hormone therapy or other unusual symptoms, call your health care provider.

References

Estrogen and progestogen use in postmenopausal women: July 2008 position statement of The North American Menopause Society. Menopause. July/August 2008;15(4)584-602.

Mosca L, Banka CL, Benjamin EJ, Berra K, Bushnell C, Dolor RJ, et al. Evidence-based guidelines for cardiovascular disease prevention in women: 2007 update. Circulation. 2007 Mar 20;115(11):1481-501.

North American Menopause Society. Estrogen and progestogen use in peri- and postmenopausal women: March 2007 position statement of The North American Menopause Society. Menopause. 2007;14:168-182.

National Osteoporosis Foundation. Clinician's Guide to Prevention and Treatment of Osteoporosis. Feb. 2008. Accessed Feb. 22, 2008.

Rossouw JE, Prentice RL, Manson JE, Wu L, Barad D, Barnabei VM, et al. Postmenopausal hormone therapy and risk of cardiovascular disease by age and years since menopause. JAMA. 2007 Apr 4;297(13):1465-77.

Review Date:8/1/2008
Reviewed By:Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Redmond, Washington ; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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