PREDICTORS OF AXIAL AND PERIPHERAL BONE-MINERAL DENSITY IN HEALTHY-CHILDREN AND ADOLESCENTS, WITH SPECIAL ATTENTION TO THE ROLE OF PUBERTY

The role of various physical and lifestyle factors in determining axia l bone mineral density (BMD) at the lumbar segment of the spine, as me asured by dual-photon absorptiometry, and peripheral BMD at the distal third of the radius, as measured by single-photon absorptiometry, was assessed in 299 healthy white children of both sexes, aged 6 to 18 ye ars. The BMD measurements were correlated with age, height, weight, bo dy mass index, and pubertal status. Peripheral and axial BMD were high ly correlated with age, height, weight, and pubertal stage, and more w eakly with body mass index. Approximately 76% of the observed changes in peripheral BMD were accounted for by age, height, weight, and puber tal stage, with weight being the single strongest predictor. Up to 80% of the variation in axial BMD was explained by weight and pubertal st age, with pubertal stage being the strongest single predictor. After a djustment for weight, the effect of puberty on axial BMD in both sexes was greatest between middle and late puberty. These data indicate tha t a large amount of the observed changes on BMD is accounted for by st andard measures of growth and development, which are largely genetical ly determined. Peripheral BMD rose steadily with age. Axial BMD increa sed steadily before puberty, followed by accelerated increases during puberty, beginning at 10 years of age in girls and 13 years of age in boys. A significant positive effect of dietary calcium intake on perip heral BMD and of physical activity on axial BMD indicated a potentiall y important impact of physical activity and calcium intake on peak bon e mass.