Ultra-Low Dose Estrogen Patch Helps Bones

May 4, 2004 (Philadelphia) -- An ultra-low dose estrogen patch reduces bone loss from menopause with few side effects researchers say.

In a new study, researchers found that the estrogen patch works alone to protect bones without increasing the risks of uterine cancer -- as seen with estrogen pills.

Gerard Nahum, MD, FACOG, associate professor at Duke University College of Medicine in Durham, N.C., tells WebMD that postmenopausal women who still have a uterus -- like the women in this study -- are usually given estrogen plus progestin since using estrogen alone greatly increases the risk of uterine cancer. However, in this study, he was especially pleased that the researchers found that the ultra-low dose estrogen patch did not cause thickening of the lining of the uterus which is an early warning sign for uterine cancer.

The study enrolled more than 400 postmenopausal women aged 60 to 80. All had thinning bones and were at higher risk of having a spine and/or hip fracture -- as indicated by bone mineral density tests. The women also had blood tests to look for markers of increased bone turnover.

The women in the study received either the patch which contained estradiol or a placebo. All the women were also given 800 milligrams of calcium and 400 IU of vitamin D daily -- both of which help prevent osteoporosis.

Researcher Bruce Ettinger, MD, of Kaiser Permanente in Oakland, Calif., tells WebMD that the ultra-low dose patch significantly increases bone density in the spine and at the hip. In general, women with the lowest blood estradiol levels -- a form of estrogen -- had the greatest benefit, he says.

The estrogen patch was also shown to reduce bone "turnover" by almost one-third. Bone turnover refers to the bone remodeling process in which old bone is dissolved and new bone is formed. Beginning at menopause this process becomes unbalanced -- more bone is dissolved than formed. This leads to an increased risk of fracture from thinned or porous bone.

Ettinger presented his results at the 52^nd Annual Clinical Meeting of the American College of Obstetricians and Gynecologists.

He says that this ultra-low dose estrogen patch offers a more natural approach to menopausal hormone therapy.

The dose in the patch is only about "one-fourth the traditional 0.625-milligram dose" contained in most estrogen pills used in menopausal hormone therapy. This means "that we are replacing circulating estrogen to the age-appropriate, normal dose, rather than trying to increase estrogen to the levels seen in young women," he says.

The study results are good news says Nahum. He tells WebMD that the new study confirms something that he and other obstetrician/gynecologists have long suspected: "A little bit of estrogen goes a long way." Nahum was not involved in the study, but he is a member of ACOG's program committee.

The patch used in the study is made by Berlex and is not yet approved by the FDA, but Ettinger says that FDA approval is expected soon -- perhaps as early as next month.