OBJECTIVE. To study the vertebral (L2-L4) and femoral (neck) bone mineral density (BMD) of normal white women. MATERIAL AND METHOD. We measured the BMD of 724 women (40-79kg; 20-69 years-age) by dual-energy X-ray absorptiometry. Data were analysed as a function of age and body weight (BW). RESULTS. Thinner women (40-49 kg) attained maximal vertebral and femoral BMD (mBMD) at ages between 30-39 years, while heavier women (60-79kg) already had the mBMD by the age of 20. At the femur, there was a significant mBMD-BW correlation (r=0.97; p<0.001; slope=0.72%/kg). At the spine, only the 40-49 Kg women exhibited lower mBMD when compared to the others (p<0.001). The decrease of the vertebral BMD was more intense (-8,3 vs. -5.7%/decade) and started earlier (fourth vs. fifth decade) in women weighting 40-59kg, as compared to those weighting 60-79kg. The decrease of the femoral BMD was initiated just after mBMD was achieved and, at the age of 69, heavier women showed a decrease that was 5.3% lower than those weighting 40-49kg. The vertebral BMD of the Brazilian women was practically the same as reported for a North-American population. CONCLUSIONS. (i) Vertebral and femoral BMD of this Brazilian population varied with age similarly to other white female populations; (ii) provided that appropriate corrections are made for BW, the BMD of Brazilian women is comparable to the BMD of North-Americans; and (iii) the BW is important both in acquisition and decline of bone mass, as it influences the relation BMD-age.
Bone mass; Bone densitometry; Bone mineral density; Body-weight; Women; Osteoporosis
