Bone, muscle, and fat: sex-related differences in prepubertal children.
OBJECTIVE
To determine whether there are sex-related differences in vertebral cross-sectional dimensions, in paraspinous muscle area, and in the amount of fat in the subcutaneous and visceral compartments of prepubertal boys and girls.


METHODS
Subcutaneous fat, visceral fat, paraspinous musculature, and vertebral cross-sectional dimensions were studied in 31 pairs of prepubertal healthy white girls and boys 5-10 years of age, rigorously matched for age, height, and weight. Data were analyzed with the Student t test and multiple regression analysis.


RESULTS
Sex had a differential effect on fat accumulation and musculoskeletal development. Compared with boys, girls had, on average, 28% greater total fat and 30% higher subcutaneous fat (P <.001 for both), but 10% less paraspinous musculature (P =.002) and 15% smaller vertebral cross-sectional dimensions (P <.001). In contrast, the sexes were monomorphic for visceral fat (P =.24). Stepwise regression analysis indicated that only 22% of the difference in vertebral cross-sectional area could be explained by sex-related differences in paraspinous musculature.


CONCLUSIONS
Together, these data indicate that sex is an important determinant of the morphology in humans well before the beginning of puberty.
Arfai
Kiumars
K
Department of Radiology, Childrens Hospital Los Angeles, 4650 Sunset Blvd, Mail Stop 81, Los Angeles, CA 90027, USA.
Pitukcheewanont
Pisit D
PD
Goran
Michael I
MI
Tavare
C Jane
CJ
Heller
Linda
L
Gilsanz
Vicente
V
D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D000886:Anthropometry; D001823:Body Composition; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D012727:Sex Characteristics; D014057:Tomography, X-Ray Computed