May 8, 2001

The first clinical trial to compare the effects of different doses of estrogen on bone turnover in older women has shown that lower doses of estrogen improve bone health, while minimizing side effects in healthy women aged 65 and older.

The principal investigator of the study, Karen Prestwood of the UConn Center on Aging at the Health Center, found that one-quarter of the current 1 mg dose of estrogen recommended as part of estrogen replacement therapy is equally effective and has fewer side-effects in older women.

Estrogen replacement therapy has long been recognized to treat symptoms of menopause, reduce bone loss, and treat osteoporosis, but women frequently experience breast tenderness, fluid retention, headaches and bloating.

The results of Prestwood's study indicate that older women may be able to reap the benefits of estrogen replacement therapy without the side effects. This should be encouraging for women who may be avoiding taking estrogen because of possible adverse effects, she said.

A group of 106 Caucasian, African-American and Hispanic women over age 65 participated in the study. After 12 weeks, bone turnover had significantly decreased in the participants taking 0.25, 0.5 or 1 mg. of estradiol, a form of estrogen. The group taking the lowest dose had no more side effects than the group taking a placebo, while the two higher doses had more side effects than the groups receiving the placebo or the lowest dose. Decreases in bone turnover among the women who took 0.25 mg of estradiol were the same as the decreases in the women who took 1 mg.

Bone turnover is the bone remodeling cycle in which new bone is formed as older bone is dissolved. Osteoporosis develops when more bone is dissolved than is formed. This process thins and weakens bones and puts individuals at serious risk for fractures, which commonly occur to the spine, wrist and hip. More than 10 million Americans have been diagnosed with osteoporosis and about 18 million are likely to develop it.

"It is possible that different women require different doses of estrogen. It is also conceivable that the same woman may require different doses of estrogen at different times in her life," says Prestwood. "We need to better understand how to treat women individually."

She cautions women already being treated with the usual dose not to arbitrarily lower their dose, however. For women having problematic side effects, a lower dose may be something to consider, but only after discussing it with their physicians.

The study was conducted at the UConn Health Center by Prestwood and Anne Kenny, assistant professors of medicine; Christine Unson, research associate at the Claude Pepper Older Americans Independence Center at the UConn Center on Aging; and Martin Kulldorff, Department of Community Medicine. The Pepper Center is one of 10 such centers funded by the National Institutes of Health that conduct research on muscle and bone problems, especially osteoporosis.

Jane Shaskan