Estrogen is prescribed for menopausal women for two reasons: to treat symptoms and to reduce the risk of certain diseases.
Women who have had a hysterectomy can use estrogen-only therapy (ET). Women who still have a uterus must protect its lining (endometrium) from estrogen overstimulation, which can lead to cancer of the endometrium. This requires a second hormone (progesterone or a progestin) that is available orally, as a vaginal cream or gel, or in the form of an intrauterine device.
The statistics on risks and benefits are not the same for ET as they are for combined hormone therapy using estrogen plus a progestogen (EPT). To avoid confusion, this article will focus on ET.
About 70 percent of menopausal women experience one or more symptoms. Hot flashes are one common symptom and probably the best known, but sleep disturbance, fatigue, small-joint pain, palpitations, chest pressure, short-term memory difficulties, feeling sad and/or anxious, and decreased sexual responsiveness and desire are almost as common. Symptoms may last for only a few months but for half of those with symptoms, they persist five to 10 years or even longer. Estrogen therapy (ET) is very effective at controlling menopausal symptoms.
The marked decline in estrogen production that occurs with menopause contributes to the development of certain diseases: atherosclerosis (a disease leading to heart attacks); osteoporosis (which can lead to bone fractures); atrophy (shrinkage) of vulva and vagina leading to urinary and sexual problems. There is also evidence that estrogen deficiency influences the development of mood disorders and brain changes that can lead to Alzheimer’s disease (AD).
ET for Disease Prevention
- Bone loss: Significant bone loss occurs in at least 40 percent of women at menopause. Rapid bone loss can result in a decrease by as much as 10 percent of their total bone mass by the time of their last period. Unchecked, bone loss leads to osteoporosis and bone fracture. When ET is started as soon as there is evidence of estrogen deficiency, bone density is maintained.
- Atrophy of the vulva and vagina (VVA): Systemic ET usually prevents shrinkage of these tissues and can reverse even severe atrophy. But sometimes, locally-applied estrogen needs to be added. Unchecked, atrophy leads to vaginal dryness, pain with intercourse, and recurrent urinary problems.
- Atherosclerosis and heart attacks: In a large U.S. study, the Women’s Health Initiative (WHI) followed approximately 10,000 women who had hysterectomies. They were given either a placebo or ET. The women who started ET before age 60 or within 10 years of their hysterectomy were 40 percent less likely to develop coronary heart disease and 46 percent less likely to have a heart attack. The reduction in death was 27 percent, almost entirely due to the reduced number of heart attacks.
- Alzheimer’s disease (AD): There is evidence that ET started close to the time of hysterectomy decreases the risk of developing AD. A study by Shao in 2012 found that women who used any type of hormone therapy within five years of menopause had 30 percent less risk of AD, especially if use was for 10 or more years and if estrogen therapy was used alone versus estrogen/progestin therapy. Previous studies have also supported a decrease in AD with estrogen use, however, the evidence for ET preventing AD is not considered definitive at this time.
- Breast Cancer: Fear of hormone treatment causing breast cancer is the leading cause for women not using any hormone therapy at menopause. This fear should not apply to ET as the findings of many studies including the WHI show that ET lowers the risk of developing breast cancer by over 20 percent. In the WHI and the Danish national hormone study, ET reduced the risk of death from breast cancer by over 60 percent.
Risks of ET
For women who start ET before age 60, the only increased risk is developing a blood clot in a vein. This risk appears to be avoided in women using transdermal (patch or gel) estrogen.
In women who start ET after age 60, the risk for venous thrombosis continues, and there is also an increase in the risk for stroke. Starting ET after age 65 does not appear to prevent heart attacks and women who start after age 70 see an increase in their occurrence.
ET should not be started without a careful medical evaluation. When using ET, it is particularly important to follow directions exactly as prescribed. Regular evaluations of the effects of ET should be done.
NAMS Position Statement. Menopause. 2012;19 (3):257-267.
LaCroix AZ, Chlebowski RT, Manson JE, et al. Health outcomes after stopping conjugated equine estrogens among postmenopausal women with prior hysterectomy: a randomized controlled trial. JAMA 2011;305(13):1305-1314.
Shao H, Breitner JC, Whitmer RA, et al. Hormone therapy and Alzheimer disease dementia. Neurology. 2012;79: 1846-1852.
Chlebowski RT, Anderson GL. Changing Concepts: Menopausal Hormone Therapy and Breast Cancer. J Natl Cancer Inst. 2012;104: 517-527.
Canonico M, Plu-Bureau G, Lowe GD, Scarabin PY. Hormone replacement therapy and risk of venous thromboembolism: systematic review. BMJ 2008;336: 1227-1231.
Zandi P. PhD et al. Hormone Replacement Therapy and Incidence of Alzheimer Disease in Older Women The Cache County Study. JAMA 2002;288:2123 2129. http://nooneshoerx.com/compounding/resources/articles/2123.full.pdf
Reviewed December 30, 2015
By Michele Blacksberg RN