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Aug. 25, 2003 — A lower dosage of estrogen than conventionally prescribed for hormone therapy increases bone density in older women without the adverse effects typically associated with estrogen therapy, according to an article in the August 27 issue of The Journal of the American Medical Association (JAMA).
According to background information in the article, osteoporosis is a major cause of disability and death in older women. Although estrogen therapy (a hormone therapy) has been shown to be effective in treating and preventing osteoporosis, many older women may be reluctant to take this drug because of adverse effects reported by the Women's Health Initiative. That report showed that women who took hormone therapy (as estrogen plus progesterone) for approximately seven years had decreased risk of hip fracture, but increased risk for breast cancer, heart disease, stroke and deep vein blood clots.
Karen M. Prestwood, M.D., of the University of Connecticut Health Center, Farmington, Conn., and colleagues investigated the effects of lower doses of estrogen (approximately one quarter of the dosage used in conventional hormone therapy) on bone loss in healthy post-menopausal women. The researchers conducted a randomized, double-blind, placebo-controlled clinical trial from July 24, 1998 through June 14, 2002 with 167 women older than 65 years old at the beginning of the study. The women were randomly assigned to receive either 0.25 milligrams per day of micronized 17beta-estradiol (n=83) or placebo (n=84).
The researchers measured bone mineral density (BMD) of the hip, spine, wrist and the total body every year for three years. They also measured biochemical markers of bone resorption (leaching of calcium from the bones) and bone formation at the beginning of the study, at three months into the study and during the first and third year of treatment.
The researchers found that the average BMD increased at all the sites measured for patients taking the low-dose estrogen compared with patients taking placebo. Participants taking the low-dose estrogen had BMD increases of 2.6 percent in the femoral neck, 3.6 percent in the hip, 2.8 percent in the spine, and 1.2 percent in the total body measurement. Biochemical markers indicating bone loss were significantly decreased in participants taking the low-dose estrogen compared to the placebo group. The researchers also found that adverse effects were similar in both the estrogen group and the placebo group.
"This study demonstrates that 0.25 mg/d of 17beta-estradiol increased BMD at important fracture sites and decreased bone turnover in older women with minimal adverse effects," the authors write. "The data from the Women's Health Initiative regarding the potential adverse effects of hormone therapy are a concern. However, our study supports a beneficial effect of lower dose estrogen on BMD and we hypothesize that lowering the dose of estrogen may also reduce the number of adverse events over a longer study period."