Hormone replacement therapy for osteoporosis

The combination of estrogen and progestin is commonly called hormone replacement therapy (HRT). For information on estrogen replacement therapy (estrogen without progestin), see estrogen for osteoporosis.

Taking estrogen brings a woman's estrogen levels back to premenopausal levels. This slows bone thinning and causes some increase in bone thickness. Progestin works like the naturally occurring hormone progesterone and prevents endometrial cancer from developing in women who have a uterus.

The Women's Health Initiative (WHI) study showed that hormone replacement therapy (HRT) can lower the risk of osteoporosis-related hip fractures and other fractures in postmenopausal women.¹ But taking HRT led to small increases in the number of women who developed breast cancer, ovarian cancer, heart attack, stroke, blood clots (pulmonary embolism and deep vein thrombosis), and Alzheimer's disease and other dementias. Most experts recommend that HRT should only be considered for women with a significant risk of osteoporosis that outweighs the risks of taking HRT.^{2, 3} To read more about this study, see WHI: Risks and benefits of taking HRT.

While hormone therapy is typically not recommended as the first choice for osteoporosis, if you are at high risk for osteoporosis and cannot take other medications, your doctor may recommend HRT. You may need to take HRT if you continue to have bone loss while taking bisphosphonate medication, such as risedronate (Actonel) or alendronate (Fosamax). In this case, you may need to take both the bisphosphonate medication and HRT. Studies show that taking a bisphosphonate with hormone therapy results in increased bone mass when compared to taking either a bisphosphonate or hormone therapy alone.^{4, 5}

Researchers are studying the effects of low-dose estrogen on women age 65 and older. An early, small study indicates that a low estrogen dose (one-quarter that of conventional ERT) may provide the same benefit—increased bone density and decreased fractures—as the higher dose. In the same study, about one-third of the women were given the low estrogen dose and progesterone (because these women did not have hysterectomies). This group of women also experienced increased bone density. However, the long-term risks of taking low-dose estrogen (and progesterone in one-third of the cases) were not studied and are unclear.^{6, 7}

Estrogen and progestin help prevent osteoporosis from developing in postmenopausal women.

A Women's Health Initiative (WHI) study showed that hormone replacement therapy (HRT) can reduce the risk for osteoporosis-related hip fractures and other fractures in postmenopausal women.¹

Common side effects include:

• Breast tenderness.
• Headache.
• Postmenopausal bleeding.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems).

You should not take HRT if you have been diagnosed with any of the following conditions:

• Pregnancy
• Uterine cancer
• Breast cancer
• Ovarian cancer
• History of or active deep vein thrombosis
• Unexplained vaginal bleeding
• Liver disease
• Stroke

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Citations

1. National Institutes of Health (2003). Women's Health Initiative. Available online: http://www.nhlbi.nih.gov/whi/.

2. Fletcher SW, Colditz GA (2002). Failure of estrogen plus progestin therapy for prevention. JAMA, 288(3): 366–368.

3. Shumaker SA, et al. (2003). Estrogen plus progestin and the incidence of dementia and mild cognitive impairment in postmenopausal women. The Women's Health Initiative memory study: A randomized controlled trial. JAMA, 289(20): 2651–2662.

4. Harris ST, et al. (2001). Effect of combined risedronate and hormone replacement therapies on bone mineral density in postmenopausal women. Journal of Clinical Endocrinology and Metabolism, 86(5): 1890–1897.

5. Greenspan SL, et al. (2003). Combination therapy with hormone replacement and alendronate for prevention of bone loss in elderly women. JAMA, 289(19): 2525–2533.

6. Prestwood KM, et al. (2003). Ultralow-dose micronized 17 B-estradiol and bone density and bone metabolism in older women. JAMA, 290(8): 1042–1048.

7. Drugs for postmenopausal osteoporosis (2008). Treatment Guidelines From The Medical Letter, 6(74): 67–74.