[Dual energy x-ray absorptiometry assessment of the bone mineral content and body composition during growth]

To propose a simple method of analysis of whole body DXA scan results, for the bone mineral content of the entire skeleton (BMCt) and the arms and legs (BMCa and BMCl), as well as the analysis of the body composition in lean (Lt, La and Ll) and fat (Ft, Fa and Fl) in children and adolescents with normal growth. Materials and methods. A whole body DXA scan (Norland XR36(TM) DXA system) was performed in 90 control females and 76 control males aged from 2.3 y to 21.0 y, and from 2.3 y to 20.1 y, respectively. BMC values, as well as L and F values were correlated with the body weight (BW) of the measured subjects. BMCt, Lt and Ft values corrected for the body surface area (BS), and the ratio BMCl/BMCa, were also calculated.

High linear correlations (r>0.9) were found between BMCt, Lt or Ft values and BW, as well as between BMC (a & l) and BMCt, L (a & l) and Lt, F (a & l) and Ft. The ratios BMCt/BS(1.5), Lt/BS(1.5), and Ft/BS(1.5) had constant values of 1.2+/-0.1, 17.5+/-1.9, and 8.7+/-2.0, respectively, in females, and 1.2+/-0.1, 18.9+/-1.3, and 7.3+/-1.4, in males. The ratio BMCl/BMCa had a constant value of 2.8+/-0.4 in both sexes.

The reference values obtained by DXA for the bone mineral content, lean and fat masses of the entire body and limbs are of interest, in our experience, to follow-up the growth in patients with long-term treatments, and to quantify orthopedic disorders and treatments.