Sex differences in the effect of body-composition variables on bone mass in healthy children and adolescents.
BACKGROUND
Prophylactic interventions against osteoporosis require a determination of the factors that influence the accumulation of bone mass during growth.


OBJECTIVE
The objective was to determine the independent sex-specific contribution of lean mass and fat mass to bone mineral content (BMC), after adjustment for anthropometric variables and lifestyle factors, in healthy children and adolescents.


METHODS
Healthy schoolchildren (184 boys and 179 girls) aged 10-17 y (x+/- SD: 13.0 +/- 2.1 y) participated in this cross-sectional study. Total and regional (lumbar spine, femoral neck, and distal one-third of the radius) BMC and body composition were measured by dual-energy X-ray absorptiometry.


RESULTS
A significant effect of anthropometric variables and lifestyle factors on BMC was observed at all skeletal sites. Lean mass and fat mass showed robust correlations with BMC, even after adjustment for anthropometric variables and lifestyle factors. Lean mass contributed to 6-12% of the variance in BMC in boys and to 4-10% in girls. Fat mass accounted for 0.1-2% of BMC variance in boys and to 0.1-6.5% in girls.


CONCLUSIONS
Both lean mass and fat mass are consistent predictors of BMC at multiple skeletal sites in healthy children and adolescents. The contribution of lean mass to BMC variance was larger in boys than in girls. In both sexes, the highest contribution of lean mass to BMC was observed at the femoral neck.
Arabi
Asma
A
Calcium Metabolism and Osteoporosis Program, Department of Internal Medicine, American University of Beirut, Lebanon.
Tamim
Hala
H
Nabulsi
Mona
M
Maalouf
Joyce
J
Khalifé
Hassan
H
Choucair
Mahmoud
M
Vieth
Reinhold
R
El-Hajj Fuleihan
Ghada
G
D015502:Absorptiometry, Photon; D000273:Adipose Tissue; D000293:Adolescent; D000886:Anthropometry; D001823:Body Composition; D015992:Body Mass Index; D015519:Bone Density; D002648:Child; D005260:Female; D006801:Humans; D008019:Life Style; D016014:Linear Models; D008297:Male; D011627:Puberty; D012727:Sex Characteristics