Bone mineral density of the lumbar spine of Brazilian children and adolescents aged 6 to 14 years

The authors performed a study of bone mass in eutrophic Brazilian children and adolescents using dual-energy X-ray absorptiometry (DXA) in order to ob tain curves for bone mineral content (BMC) and bone mineral density (BMD) b y chronological age and correlate these values with weight and height. Heal thy Caucasian children and adolescents, 120 boys and 135 girls, 6 to 14 yea rs of age, residents of Sao Paulo, Brazil, were selected from the Pediatric Department outpatient clinic of Hospital Sao Paulo (Universidade Federal d e Sao Paulo). BMC, BMD and the area of the vertebral body of the L2-L4 segm ent were obtained by DXA. BMC and BMD for the lumbar spine (L2-L4) presente d a progressive increase between 6 and 14 years of age in both sexes, with a distribution that fitted an exponential curve. We identified an increase of mineral content in female patients older than 11 years which was maintai ned until 13 years of age, when a new decrease in the velocity of bone mine ralization occurred. Male patients presented a period of accelerated bone m ass gain after 11 years of age that was maintained until 14 years of age. A t 14 years of age the mean BMD values for boys and girls were 0.984 and 1.0 17 g/cm(2), respectively. A stepwise multiple regression analysis of paired variables showed that the "vertebral area-age" pair was the most significa nt in the determination of BMD values and the introduction of a third varia ble (weight or height) did not significantly increase the correlation coeff icient.