Conference Report From the 10th World Congress on the Menopause

Professor Lorraine Dennerstein, AO MBBS, PHD, DPM, FRANZCP

Disclosures

July 03, 2002

In This Article

The Effects of Hormonal and Lifestyle Factors on BMD

In the same session, Dr. Guthrie utilized the Melbourne data to explore the effects of hormonal and lifestyle factors on BMD. One hundred and fifty three of the Melbourne women underwent dual-energy x-ray absorptiometry measurement of BMD at the lumbar spine and proximal femoral neck on 3 occasions. Guthrie and colleagues[24] have reported a significant decline in BMD at the lumbar spine and femoral neck as women entered the late menopausal transition, with reports of at least 90 days of amenorrhea. The decline in BMD was greater at the lumbar spine than at the femoral neck. In the conference presentation, using linear regression, Guthrie and colleagues[4] showed that change over time in BMD was dependent on the log of the estradiol level and that no other hormone level measured had a significant effect on BMD. The level of estradiol needed to maintain BMD can be estimated. This should allow clinicians to better calculate the minimum amount of estrogen replacement needed to maintain BMD and prevent further bone loss.

Professor MaryFran Sowers,[25] of the University of Michigan, Ann Arbor, presented information from SWAN. At baseline, participants in this study were aged 42-52 years, had menstruated in the prior 3 months, and were selected to include African American women, Asian (Chinese and Japanese) women, and white women. Approximately 450 women we selected for study at each of 7 sites. Significant ethnic variation in BMD was evident at baseline, with African American women having the highest levels and Japanese women the lowest levels. Professor Sowers also indicated that BMI was so different between ethnic groups at baseline that there were difficulties in utilizing the traditional techniques used for statistical adjustment for covariates. African American women have significantly higher weight at baseline -- 10 kg higher than white women and 15 kg higher than Asian women. As well, African American women had significantly more pregnancies than other ethnic groups.

There were other important lifestyle differences between ethnic groups in a manner that may affect health outcomes. For example, Chinese women were less likely to smoke cigarettes or to drink alcohol. White women consumed more calcium. After adjusting for covariates, African American women continued to have the highest levels of BMD, but the BMD of other ethnic groups did not differ significantly from each other. Of baseline hormones measured, only FSH was associated (inversely) with BMD. FSH was significant after adjusting for covariates including ethnicity, site of BMD measurement, and lifestyle factors. This indicates hormonal effects on BMD. However, this baseline analysis should be regarded as preliminary until longitudinal data are available.

These findings are not at variance with Guthrie and coworkers' longitudinal findings of the association of bone loss with estradiol decrease.[26] In the early phase of the menopausal transition, FSH may be a better and more stable indicator of changing ovarian functioning. In an analysis performed when the Melbourne study had access to only 5 years of longitudinal data, we found that FSH had a stronger relationship with sexual functioning than did estradiol.[26] In the most recent analysis based on up to 9 years of follow-up, we found that estradiol was the only hormone significantly affecting aspects of sexuality (see above). These findings, among others, lend credence to the selection of increasing FSH as the endocrine marker of the early phase of the menopausal transition. Clinical implications of the findings of SWAN are that there are differences in BMD between ethnic groups, and that adjustment should be made for BMI.

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