Bone Up on Hormone Replacement Therapy

From the WebMD Archives

April 13, 2001 -- After menopause, women start to lose bone in critical areas of the skeleton, placing them at risk for bone fractures. For years now, experts have said that taking hormone replacement therapy after menopause is one of the best ways to slow bone loss and prevent these fractures and the loss of height that occurs as women age. Now a new study says that in women who don't actually have osteoporosis, hormone replacement may not be doing the trick.

Bone loss is linked to the sharp decline in a woman's natural levels of the hormone estrogen that occurs around menopause. Significant bone loss leads to the brittle-bone disease osteoporosis.

Although studies in women with osteoporosis have indicated that hormone replacement therapy may substantially reduce fracture risk, results of studies conducted in women without osteoporosis have been mixed.

And these new findings, published in the April 15 issue of the American Journal of Medicine, don't help to clarify the situation much.

The study raises suggests that hormone replacement therapy, or HRT, may not be effective at preventing fractures among women who don't have established osteoporosis, says study author Jane Cauley, DrPh, of the University of Pittsburgh. She says any usefulness of the therapy in preventing fractures may be restricted to those women who already have the brittle-bone disease.

The four-year study of more than 2,700 women aged 44-79 found no difference in the incidence of fractures and no difference in height loss between women taking hormone replacement -- either estrogen alone or estrogen plus progestin -- and women taking no hormones.

But Robert Recker, MD, disagrees that this new study rules out HRT or estrogen as an effective way to reduce fractures. He argues this because of the way the study was conducted. Although the authors collected data on fractures, the main goal of the study was to study the effect of the hormones on heart disease -- not the effect on fractures.

And because the women in the study did not have osteoporosis, he says, there is no way to know that they would be the best candidates for the therapy.

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"This does not in any way change my mind about the potential benefits of HRT or estrogen in preventing fractures," says Recker, who is director of the Osteoporosis Research Center at Creighton University School of Medicine in Omaha, Neb. He says that many other studies have shown that HRT increases bone mass and that a few studies have shown that the therapy also can reduce the risk of fractures.

Recker says in addition to those, other studies suggest that the estrogenlike drug raloxifene, which is sold as Evista, is very effective at reducing the risk of spine fractures. Since estrogen and Evista work similarly, he says there's no reason to believe that estrogen would be any less effective at reducing fractures when taken for five years or more.

The biggest problem, he says, is that almost no studies have looked at postmenopausal women long enough to determine whether estrogen or estrogen plus progestin leads to fewer fractures as they age. One ongoing study -- the Women's Health Initiative -- is attempting to do this, but it is not scheduled to be completed until 2004.

"We just have to wait. I think the evidence is pretty clear that estrogen will slow or prevent bone loss. Now, whether over the years that will translate into fracture reduction, nobody knows," says C. Conrad Johnston Jr., MD, president of the board of trustees of the National Osteoporosis Foundation and a professor of medicine at Indiana University School of Medicine in Indianapolis. "But the evidence suggests that the earlier you take it, the more of an effect it will have."

Johnston says his advice to women wondering about whether to start or continue taking hormones to prevent fractures is, "don't throw the baby out with the bathwater" based on this study alone.

According to the National Osteoporosis Foundation, 8 million women in the U.S. have osteoporosis, which puts them at significantly increased risk for bone fractures as they age. Another 14.4 million women have low bone mass, which also increases the risk of fractures.

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