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New Study Supports the Value of Measuring Estrogen Levels in Postmenopausal Women Treated with Hormone Replacement Therapy Reports Researcher at the University of Pittsburgh School of Pharmacy

PITTSBURGH, October 16, 2003 New findings demonstrate that levels of the most potent estrogen - estradiol - vary substantially among postmenopausal women treated with hormone replacement therapy (HRT). In addition, the factors that influence the estrogen level achieved among HRT-treated women have been identified by researchers at the University of Pittsburgh School of Pharmacy.

These findings are reported in the October issue of the Journal of Women's Health. The results of this study may help clinicians and other researchers resolve the controversy about the benefits and risks of HRT.

Until recently, HRT was an acceptable treatment for postmenopausal symptoms such as hot flashes, fatigue and mood swings. In addition, HRT was used to decrease the risk of coronary heart disease and osteoporosis. However, with the early termination of the Women's Health Initiative randomized clinical trial, the ongoing controversy about the benefits and risks of HRT has reached new heights.

"This study is a natural experiment. In our study of postmenopausal women from all major racial and ethnic groups who were being treated by their own physicians with HRT for an average of 11 years, first we measured estradiol levels, and then we developed a systematic method to classify the estradiol levels achieved among the women being treated with HRT. Estrogen levels are not routinely monitored in HRT-treated women; in fact estrogen levels are rarely measured in HRT-treated women. This makes no sense to me. For example, when drugs designed to lower cholesterol are studied, cholesterol levels are measured. Why would measuring estrogen levels in women treated with estrogen/hormone replacement therapy not be routine?" noted Judith S. Gavaler, Ph.D., research professor emeritus in the department of pharmaceutical sciences at the University of Pittsburgh School of Pharmacy.

The data for this report came from the observational Postmenopausal Health Disparities Study, which was performed in Oklahoma City between 1993 and 1999, and has been continuing in Pittsburgh. The researchers looked at 325 postmenopausal women being treated with either oral or patch HRT, and 291 untreated control women. "Response" categories for the estradiol levels achieved in HRT-treated women were based on average and the measure of variability for the average, (the standard deviation) in the untreated control women. The response categories ranged from the control mean less 1 standard deviation to the control mean plus 6 standard deviation.

"The percentage of HRT-treated women whose estradiol levels were in the lowest category ranged from 40 to 43 percent across the racial groups. These women could be described as being similar to the controls as far as risk of coronary heart disease and osteoporosis because they are receiving neither benefit nor risk from the use of HRT. The highest category, contained from 9 percent to 14 percent of women from the five major racial groups. These women may be at high risk of breast cancer. It is possible that both ineffective HRT treatment and over-treatment could be avoided if treating physicians routinely measured estradiol levels," noted Dr. Gavaler.

Predictive factors were identified that explained more than 50 percent of the variability in the estradiol levels achieved in HRT-treated women. Negative predictors included poor medical compliance, lower body fat mass, use of the patch, menopause duration, and being a white woman (European American). Positive predictors included alcoholic beverage consumption, previous removal of the ovaries, and markers of factors within individuals involved in estradiol production.

"This is an important study because it demonstrates that the measurement of estradiol levels can provide the necessary information to maximize the benefits of estrogen/HRT treatment and to minimize the dangers of estrogen/HRT treatment in women from all racial groups. I hope that researchers will accept these new findings by incorporating the measurement of estradiol levels in estrogen/HRT treatment in all women, both in clinical practice and in the setting of clinical trials. Routine measurement of estradiol levels may not only improve the health of women from all racial groups, but also lay the HRT controversy to rest," stated Dr. Gavaler.

This research has been supported by the National Institutes of Health (NIH) Office of Women's Health Research, the office of Minority Health and grants from the National Institute on Alcohol Abuse and Alcoholism. It is interesting to note that the Postmenopausal Health Disparities Study started before the NIH mandated the inclusion of women and minorities in clinical research.

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