Hormone Replacement Therapy (HRT)
- Symptoms and Effects of Menopause
- Common Regimens of HRT
- Heart Disease and HRT
- HRT and Osteoporosis
- HRT and Alzheimer's Disease/Dementia
- HRT and Diabetes
- Negative Effects of HRT
- HRT and Breast Cancer
- The Women's Health Initiative Finds Risks with HRT
- Additional Resources and References
Estrogen and progestin are the two hormone supplements most often used in HRT. Taking estrogen without progestin to balance the hormonal cycle may cause over-stimulation of the endometrium tissue, the lining the uterus. This may lead to uncontrolled tissue growth called hyperplasia, which may lead to endometrial cancer. Progestin counteracts this risk. Therefore, women who have not had their uteruses removed are usually prescribed estrogen and progestin together. Progestin may also be prescribed alone, usually to prevent hot flashes or other menopausal problems.
Premarin, the most commonly prescribed estrogen used with HRT, is a conjugated estrogen. Premarin contains a mixture of natural estrogen from the urine of pregnant mares. Some research has shown that conjugated estrogens may prevent heart disease and osteoporosis. Esterified estrogen, derived from plants, may increase bone density. Estradiol is the most potent estrogen and is available in a variety of forms. The most common forms of HRT are pills and skin patches.
Heart disease is the leading cause of death in post-menopausal women. Since a woman's risk of heart disease increases significantly at menopause, when her body stops producing estrogen, researchers have long been interested in determining whether HRT can help protect women against heart disease.
Past studies have provided hope that HRT can reduce heart disease risk. For example, studies have also shown that HRT may prevent the spasm of arteries that deliver blood and oxygen to the heart and lower the level of proteins that may cause harmful blood clots in those arteries. Studies showed that estrogen therapy may also help heal damaged blood vessels, prevent blood from coagulating (thickening), and may help to keep the walls of blood vessels pliable and open. In a 1997 study reported in the medical journal, Obstetrics and Gynecology, researchers found a lower incidence of coronary artery calcification in women who took HRT. Moreover, according to epidemiologist Deborah Grady, MD, for patients who have already had one heart attack, HRT may reduce the chance of a second heart attack by 84%.(3) Estrogen/progestin combinations may also help decrease heart disease by working to lower LDL ("bad") cholesterol levels and increasing HDL ("good") cholesterol levels.
However, recent studies have contradicted the beneficial effects of HRT on the heart. In fact, these newer studies suggest that HRT may actually increase the risk of heart disease in some women. In July 2002, the National Institutes of Health (NIH) stopped short a major study of HRT, called the Women's Health Initiative, because early findings showed that HRT was harmful to the heart. The NIH found that for every 10,000 women who take a combined estrogen/progestin version of HRT, 7 more will have a heart attack, 8 more will have a stroke, and 18 more will have blood clots, including 8 with blood clots in the lungs. A further analysis of the study's results showed that estrogen plus progestin use was associated with a 24% overall increase in the risk of heart disease, with an 81% increased risk in the first year of use The study did find benefits to HRT, including fewer hip fractures (often a sign of osteoporosis) and a decreased risk of colon cancer.
Risk factors for heart disease include:
- previous heart attack
- high blood pressure
- atherosclerosis (narrowed arteries)
- diabetes mellitus (a disorder caused by failure of the pancreas to release enough insulin into the body)
- family history of heart disease
- high cholesterol
- excessive consumption of alcohol
- lack of exercise
Osteoporosis is a degenerative bone disease that affects approximately one third of women over age 50. HRT is commonly prescribed to help prevent osteoporosis in post-menopausal women and appears to be particularly effective against osteoporosis if taken during the first five years after menopause begins. It is estimated that HRT can lead to a 50% to 80% decrease in vertebral fractures and a 25% decrease in non-vertebral fractures with five years of use. However, women may lose protection once they have stopped taking HRT. The Women's Health Initiative study results also showed HRT to be beneficial for bone health. On average, the researchers found that if a group of 10,000 women takes estrogen plus progestin for a year, 5 fewer cases of hip fractures will occur than in 10,000 nonusers.
Risk factors for osteoporosis include:
- advancing age
- female gender and post-menopausal
- family history of osteoporosis
- thin or small build
- Caucasian or Asian
- excessive alcohol
- too little exercise or physical activity (sedentary lifestyle)
- low calcium intake (now or as a child)
- use of certain medications, such as steroids (commonly used to treat asthma and arthritis)
- high doses of thyroid hormone
- menopause before age 45
- back pain
- height loss (indicates collapse of a spinal vertebra)
- curving spine
- broken bone (especially from a minor fall or non-traumatic event)
- history of broken bones from minor injuries
- chest x-ray showing osteopenia and/or vertebral wedging or collapse
HRT may also prevent osteoarthritis, a degenerative joint disease. Osteoarthritis is a major cause of hip and knee replacement surgeries among the elderly. As with osteoporosis, protection against osteoarthritis ends after HRT has been stopped.
However, HRT is not the only option for women considering osteoporosis prevention or treatment. In addition to HRT, patients can help decrease the risk of osteoporosis by taking calcium, magnesium, vitamin D, exercising or taking medications such as raloxifene (brand name Evista), alendronate (brand name Fosamax), calcitonin (brand name, Miacalcin), or risedronate sodium (brand name, Actonel).