RELATIONSHIP OF BODY COMPOSITION, ANTHROPOMETRICS, AGE AND GENDER TO BONE MINERAL DENSITY IN CHILDREN

Abstract

Total body bone mineral density (BMD) has been associated with both lean tissue mass (LTM) and fat tissue mass (FTM) in adults and children. However, the relationship between regional BMD and soft tissue mass has not been adequately studied in children. PURPOSE The purpose of this study was to determine the relationships between body composition, anthropometrics, age, gender and BMD in children. METHODS Total body BMD and body composition were measured using dual-energy x- ray absorptiometry (Lunar DPX). Values for regional arm and leg BMD, LTM and FTM were determined from the total body measurement. Pearson correlations were used to examine the relationships between body composition, height, weight, circumferences, age and BMD. Stepwise multiple regression was used to determine the predictors of total body, arm and leg BMD. RESULTS Participants were male (n = 121) and female (n = 115) children aged 5.0 to 12.2 yr. Mean (±SD) age, height, weight, arm and calf circumferences were 9.5 ± 1.2 yr, 135.8 ± 10.0 cm, 35.9 ± 11.5 kg, 20.6 ± 2.7 cm and 28.6 ± 3.8 cm, respectively. Mean (±SD) total body BMD, FTM and LTM were 0.91 ± 0.07 g/cm2, 9.7 ± 7.5 kg and 24.4 ± 4.8 kg, respectively. Significant correlations were found between BMD and LTM, FTM, weight, height, arm circumference, calf circumference and age (r = 0.46 to 0.85, p < 0.01). The significant predictors of total body BMD using stepwise multiple regression were total LTM, total FTM, age and height (R2 = 0.62, p < 0.001). The significant predictors of leg BMD were leg LTM, leg FTM, age and height (R2 = 0.79, p < 0.001). However, only arm LTM, age and height were significant predictors of arm BMD using stepwise multiple regression (R2 = 0.58, p < 0.001). Neither gender, weight, nor circumferences were significant predictors of BMD at any site. CONCLUSION In preadolescent children, LTM, age and height are better predictors of total body and regional BMD than FTM, total body weight, arm and calf circumferences or gender. Supported by General Mills, Inc. and NIH Grant R01 HD36616-03.