NEW YORK (Reuters Health), Jul 26 - Similar to what has been shown in young adults, adipose tissue appears to stimulate bone growth in prepubertal children, British researchers report. After puberty, this effect is weakened.
In a study reported in the Journal of Clinical Endocrinology and Metabolism for July, the fat mass in children was an independent predictor of bone mass and size as well as increases in these parameters over the next two years.
There were some reasons to believe that adipose tissue in children would have just the opposite effect to what was seen in adults, senior author Dr. J. H. Tobias, from the University of Bristol in the U.K., and colleagues note. In young age groups, adipose tissue has been shown to express enzymes that generate estrogen, a known inhibitor of periosteal bone growth. In addition, fat tissue may mediate reduced bone growth through increased levels of leptin.
Conversely, it is possible that the increased load seen with an elevated fat mass stimulates bone growth, the authors point out.
The study involved 3,082 children, mean age 9.9 years, drawn from a population-based cohort in southwest England. Dual-energy x-ray absorptiometry was used to assess body fat mass at baseline and to assess bone mass at baseline and over the next two years.
Even after accounting for height and lean body mass, total body fat mass showed a strong, direct association with bone mass and area, the authors state.
As noted, the fat mass was also predictive of increases in bone mass and area over the next two years. However, this positive correlation was confined to boys and to girls of Tanner stage 1. In Tanner stage 2 girls, no association was seen, while in stage 3 girls a negative correlation was noted. A significant interaction between puberty and fat mass was observed.
This suggests that "the onset of puberty leads to attenuation of the tendency for fat mass to stimulate periosteal growth," the researchers note.
"Taken together, these observations provide strong evidence that adipose tissue acts to stimulate bone growth in prepubertal children," the authors conclude. "Because the relationship between fat mass and bone size in models that included lean mass was only minimally affected by additional adjustment for height, our results suggest that fat mass acts to increase bone size by stimulating radial rather than longitudinal bone growth presumably by increasing the rate of periosteal apposition."
Last Updated: 2006-07-25 18:32:24 -0400 (Reuters Health)
J Clin Endocrinol Metab 2006;91:2534-2541.
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