Total body bone mineral density in young children: influence of head bone mineral density.

Dual-energy X-ray absorptiometry (DXA) with its short scan time, low radiation dose, and high precision and accuracy have made this technique particularly suitable for measuring total body bone mineral density (TBMD) in children. Other published reports have related TBMD to age in children 2-18 years of age. However, in young normal children aged 2-9 years (51 girls, 43 boys), we found that regression equations for TBMD with age as the predictor did not explain enough of the variance to warrant their use for predicting TBMD (adjusted R2 0.47, females; 0.41, males). Subtotal BMD (TBMD-head BMD) is predicted better by age because of a possibly invalid adult algorithm for head BMD (adjusted R2 0.73, females; 0.71, males).