"Estrogen Therapy and Osteoporosis"
For women at risk of osteoporosis, a doctor may recommend estrogen when the body’s production of the
hormone drops, that is, during and after menopause. Menopause occurs naturally around the age of 50, although it can occur when a woman is in her late 30s or
into her early 60s. Menopause also will occur if the
ovaries are removed by surgery.
Many experts feel that, in terms of its effects against
osteoporosis, the benefits of estrogen replacement outweigh its risks. The decision to use estrogen,
however, is one that should be made carefully by a woman and her doctor, Individuals would be wise to
consider the benefits, risks and costs of all medications and procedures.
There is evidence that low-dose estrogen is highly effective for the prevention and possibly treatment of
osteoporosis in women. Estrogen reduces the amount of calcium taken out of bones and thus slows or halts
postmenopausal bone loss.
It cannot, however, restore bone mass to premenopausal levels. Studies have shown that women who have begun
taking estrogen within a few years after the onset of menopause have fewer hip or wrist fractures and possibly
fewer spinal fractures than women who do not take estrogen. Even when started as late as 6 years after
menopause, estrogen therapy reduces further loss of bone. There is also some scientific evidence that estrogen
replacement therapy confers some protection against cardiovascular disease. It is thought to raise blood levels of
a fraction of cholesterol known as “HDL” or high density lipoprotein and to lower blood levels of “LDL” or low
density lipoprotein. Raised HDL levels and lowered LDL levels are associated with lower rates of heart and blood
On the risk side of the ledger, estrogen replacement therapy is thought to increase the risk of a type of cancer
of the uterus known as endometrial cancer from 1 per 1,000 women to about 4 per 1,000 women. It is not a problem for a woman who has had her uterus removed.
Estrogen is not linked to breast cancer, according to most
Estrogen replacement therapy may also increase the risk of
blood clot formation (thrombosis). In women on estrogen replacement therapy, periodic bleeding may resume.
(Because estrogen therapy may cause the lining of the uterus to build up, it is often prescribed on an on-and-off
basis -- for example, 20 days on the drug, then 10 without it -- so that the uterus lining can be shed during the days
off the hormone.)
Sometimes, estrogen is combined with another female hormone,
progestin, also called progestogen. (Progesterone is one form of progestin.) Progestins may
reduce the risk of endometrial cancer. There is preliminary evidence that they may reduce bone loss.
There is little information on the long-term risks or benefits of estrogen combined with progestin in
postmenopausal women. Studies on younger women taking progestins in birth control pills have shown an
increased risk of high blood pressure and of disorders of the heart and blood vessels. Moreover, some progestins
may blunt or do away with estrogen’s protective effects against heart disease.
Until more data on the risks and benefits of estrogen replacement are available, doctors and patients may prefer
to reserve estrogen (whether or not it is combined with a progestin), for situations in which there is a moderate to
high risk of osteoporosis and its complications occurring. Premature menopause -- especially through surgical
removal of the ovaries several years before the time of natural menopause -- places a woman at high risk of
osteoporosis. Postmenopausal women having risk factors other than an early menopause may also want to discuss
estrogen therapy with their doctors.
The recommendations above, according to the National Institute of Arthritis and Musculoskeletal and Skin
Disorders, apply mainly to Caucasian women who are
considered to be at increased risk for osteoporosis. Women of other races and their doctors might consider
estrogen on a case-by-case basis. There is no good
evidence that elderly women should be started on estrogen therapy to prevent osteoporosis.