Lower doses of estrogen alone or in combination with a progesterone-like drug increase mean bone-mineral density, according to a new Wayne State University School of Medicine study published recently in Osteoporosis International.

In a two-year study assessing the impact of hormone-replacement therapy on bone loss, women who took lower doses of estrogen alone or in combination with a progesterone-like drug suffered significantly less bone loss in their spines and hips than women who took a placebo. The study, which was conducted at four U.S. universities, was led in Detroit by Michael Kleerekoper , WSU professor of medicine in the Division of Endocrinology.

"The message of the article is that even in low doses estrogen prevents bone loss at menopause in the vast majority of women. That's exciting news when you consider that women experience up to 20 percent of their lifetime bone loss in the five to seven years after the menopause," Dr. Kleerekoper said. "The need to give every woman the old standard, one-size-fits-all dose is gone."

In the randomized, double-blind study, 822 healthy postmenopausal women with intact uteri received either a placebo or varying doses of conjugated estrogens alone or in combination with two different doses of medroxyprogesterone acetate. The women also took 600 mg of calcium per day.

More than 85 percent of women receiving hormone therapy experienced no additional bone-mineral density loss at one year and two years, in comparison to 30.6 percent of women on placebo at 12 months and 36.5 percent of women on placebo at 24 months.