Period of rapid BMD loss identified in middle-aged women
MedWire News: Results of a US study show that there is a period of rapid bone mineral density (BMD) loss surrounding the final menstrual period (FMP) in middle-aged women.
At both the lumbar spine and femoral neck, BMD loss began 1 year before the FMP and slowed 2 years after it, report Gail Greendale (University of California, Los Angeles) and co-investigators. Furthermore, this period of BMD loss was independently influenced by ethnicity and body mass index (BMI).
Their analysis included 242 African American, 384 White, 117 Chinese, and 119 Japanese pre- or early perimenopausal women, aged between 42 and 52 years at baseline.
The women had their lumbar spine and femoral neck BMD measured annually for 10 years, and all had experienced their FMP by the final follow up.
Loess-smoothed curves of normalized BMD showed no measureable decline in BMD at both bone sites before 1 year before the FMP.
Bone loss began 1 year before FMP, and decelerated, but did not cease, 2 years after the FMP. This "transmenopausal" BMD loss was greater at the lumbar spine than the femoral neck.
Specifically, the cumulative 10-year BMD loss at the lumbar spine was 10.6%, with 7.38% lost during the transmenopause. The cumulative 10-year BMD loss at the femoral neck was 9.1%, with 5.8% lost during the transmenopause.
Postmenopausal loss rates, defined as starting 2 years after the FMP, were less than the transmenopausal rates of loss and were of similar magnitude at each bone site.
Of interest, greater BMI and African American origin were related to slower loss rates, whereas the opposite was true for Japanese and Chinese ancestry, note the authors in the Journal of Bone and Mineral Research.
They propose that rapid transmenopausal BMD loss could permanently damage skeletal structural integrity, and suggest that future work should focus on the effect of BMD loss on bone microarchitecture and bone strength. "Clinically useful signals that presage the onset of transmenopausal BMD loss also require elucidation," they conclude.
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By Nikki Withers