Site-specific effects of trunk fat mass on bone mineral density in a group of adolescent girls

Abstract

Introduction The aim of this study was to explore the relation between trunk fat mass on one hand and non-dominant arm (non-weight-bearing site) bone mineral density (BMD) and total hip (weight-bearing site) BMD on the other hand in a group of adolescent girls. Subjects and methods This study included 45 post-menarchal adolescent (aged 13–20 years) girls. Anthropometric characteristics (height and weight) were measured and body mass index (BMI) was calculated. Body composition (lean mass, fat mass, body fat percentage and trunk fat mass), BMC and BMD of the left arm and total hip BMD were assessed by dual-energy X-ray absorptiometry (DXA). The tissue composition of the left arm was determined from the regional analysis of the whole-body DXA scan. The arm region included the hand, forearm, and arm, and was separated from the trunk by an inclined line crossing the scapulo-humeral joint. Results Trunk fat mass was strongly correlated to total hip BMD (r = 0.57; P < 0.001) but was not related to left arm BMD. The correlation between trunk fat mass and total hip BMD remained significant after adjusting for lean mass. Conclusion This study suggests that trunk fat mass is a positive determinant of total hip BMD but not of non-dominant arm BMD in adolescent girls.