The aim of this study was to evaluate the influence of leptin on biochemical markers of bone metabolism in childhood obesity.

A total of 50 male children (25 obese and 25 controls) were recruited from the pediatric outpatient clinic at the Chosun University Hospital from November 1st 2005 to May 30th 2006. BMI, body fat percentage, serum leptin, bone-specific alkaline phosphatase (B-ALP), C-terminal propeptide of type 1 collagen (CICP), total deoxypyridinoline crosslinks (total DPD) were measured. The correlations of leptin with BMI, body fat percentage, B-ALP, CICP, total DPD were analyzed by Pearson's correlation. In a multiple stepwise regression analysis, leptin after correction for body weight was evaluated if there was a correlation with biochemical markers of bone formation and resorption respectively.

The leptin levels of the obese group were significantly higher than those of the control group (p=0.012). In the obese group, the leptin level was significantly positively correlated with the BMI (r=0.551, p=0.01) and the percentage of body fat (r=0.584, p=0.018). In the obese group, of bone markers, B-ALP (r=−0.613, p=0.026) and CICP (r=−0.583, p=0.037) were negatively correlated with leptin. B-ALP (r=−0.728, p=0.007) and CICP (r=−0.684, p=0.014) were negatively correlated with leptin when corrected for body weight. In the control group, bone markers were not correlated with leptin. In the multiple stepwise regression analyses, there was a negative correlation between the leptin and B-ALP (Y=−39.653X+356.341, p=0.026), CICP (Y=−13.437X+116.013, p=0.037) respectively in the obese group.

Leptin was a significant factor in the bone formation but not in bone resorption in childhood obesity.