Premenopausal and postmenopausal changes in bone mineral density of the proximal femur measured by dual-energy X-ray absorptiometry.
Total and regional bone mineral density (BMD) of the proximal femur was measured by DXA in 1238 healthy white women. In the 389 premenopausal women, aged 21-54 years, no bone loss was observed before the menopause, except in the femoral neck and Ward's triangle, in which BMD decreased by 0.3%/year (SEE 0.2-0.9%/year, p < 0.001) and 0.6%/year (SEE 0.4-0.8%/year, p < 0.001), respectively. In the postmenopausal women aged 48-75 years, there was a highly significant exponential decay in BMD with age and years since menopause (YSM) in all regions (-0.58 < r < -0.48, p < 0.001). However, YSM was a better predictor of BMD than age. The decrease in BMD in the first 5 years postmenopause reached values of 9-13%. The estimated bone loss after 20 years was 17-30%, greatest in Ward's triangle and smallest in the intertrochanteric region. BMD correlated highly significantly with BMI (0.26 < r < 0.48, p < 0.001). In conclusion, the present study indicates a stable premenopausal bone mass of the proximal femur and a postmenopausal bone loss, which is influenced mainly by YSM within the first 10-15 years after menopause. BMD correlated with body mass index (BMI) in the postmenopausal years, confirming that low BMI constitutes a potential risk factor for osteoporosis.
Ravn
P
P
Center for Clinical and Basic Research, Ballerup, Denmark.
Hetland
M L
ML
Overgaard
K
K
Christiansen
C
C
D015502:Absorptiometry, Photon; D000328:Adult; D000367:Age Factors; D000368:Aged; D015519:Bone Density / Q000502:physiology*; D005260:Female; D005269:Femur / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D017698:Postmenopause / Q000502:physiology*; D017697:Premenopause / Q000502:physiology*