Journal Article

Natural History of Bone Loss over 6 Years among Premenopausal and Early Postmenopausal Women

K. E. Bainbridge, MF. Sowers, M. Crutchfield, X. Lin, M. Jannausch and S. D. Harlow

in American Journal of Epidemiology

Published on behalf of Johns Hopkins Bloomberg School of Public Health

Volume 156, issue 5, pages 410-417
Published in print September 2002 | ISSN: 0002-9262
Published online September 2002 | e-ISSN: 1476-6256 | DOI:
Natural History of Bone Loss over 6 Years among Premenopausal and Early Postmenopausal Women

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The aims of this prospective cohort study were to determine rates of premenopausal and early postmenopausal bone loss, age at onset of bone loss, and whether rates of bone loss depend on baseline bone mineral density (BMD). The cohort of 614 women aged 24–44 years at baseline from the longitudinal Michigan Bone Health Study was followed for 6 years beginning in 1992–1993. Up to five BMD measurements of the lumbar spine (L2–4) and the femoral neck were obtained through 1998–1999 by using dual x-ray absorptiometry and were standardized (as z scores) relative to a young adult, female BMD distribution. Regression models were used to estimate rates of BMD change and to examine BMD as a function of age. At the lumbar spine, the rate of BMD change for premenopausal women varied with time. At the femoral neck, the rate of change was –1.6% (95% confidence interval: –0.9%, –2.3%) of a z score annually (annual loss of 0.3% of baseline BMD (g/cm2)). Evidence for age at onset of bone loss at the lumbar spine was inconclusive. Bone loss began by the midtwenties at the femoral neck. Additional annual change of –0.7% (95% confidence interval: –0.2%, –1.2%) of a z score was observed at the femoral neck for each unit increase in BMD z score at baseline.

Keywords: bone density; longitudinal studies; menstrual cycle; osteoporosis, postmenopausal; premenopause; Abbreviations: BMD, bone mineral density; BMI, body mass index; TCHS, Tecumseh Community Health Study.

Journal Article.  5781 words.  Illustrated.

Subjects: Public Health and Epidemiology

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