Annual changes in bone mineral content and body composition during growth.
OBJECTIVE
To compute the annual changes in total bone mineral content (BMCt), lean tissue mass and fat mass (LTM and FM) during growth.


METHODS
Whole body DXA data were used to calculate the annual changes of the parameter P (P = BMCt, LTM or FM), as a percentage, as DeltaP% = 100 x (P(i+1) - P(i)) / P(i); with P(i) and P(i+1) the values for P at age i and age (i+1). Smoothed curves were then obtained from DeltaP% values plotted against age.


RESULTS
Changes in FM were different in males and females. A peak velocity was marked for the three tissues at age 6.5 in boys, and at age 6.5-7.5 in girls; a pubertal peak spurt appeared at age 12 in girls and between age 13 and 14 in boys. This latter peak was followed by an exponential decrease, and no significant changes were found for the three components after age 20 in girls and age 21-22 in boys.


CONCLUSIONS
Changes in tissue accretion during growth are easy to follow when expressed in percentages. Fat changes, especially, should be around 17% in girls and 15% in boys at the age of puberty.
Braillon
P M
PM
Department of Pediatric Imaging, Hospital Debrousse and University Claude-Bernard, Lyon, France. pierre.braillon@chu-lyon.fr
D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000502:physiology; D000293:Adolescent; D000328:Adult; D001823:Body Composition / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006128:Growth / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D010507:Periodicity; D011627:Puberty / Q000502:physiology; D013997:Time Factors