Aim: Complex correlations exist between leptin, obesity and bone formation. Leptin is thought to affect growth and bone formation as well as osteoblastic and osteoclastic activities. Additionally, leptin increases bone mineral content. The aim of this study was to evaluate the correlation between serum leptin levels and osteoblastic and osteoclastic parameters and Bone Mineral Density (BMD) in children with exogenous obesity.
Patients and method: Forty-five children with exogenous obesity, aged 6-17 years (27 girls and 18 boys) who were followed up at the Eskisehir Osmangazi University Faculty of Medicine, Department of Pediatrics, were enrolled. Thirty-nine healthy children, aged 6-17 years (17 girls and 22 boys), were assigned to the control group. In addition to serum leptin, serum osteocalcin was measured as an indicator of osteoblastic activity, and urine Deoxypyridinoline/Creatinine ratio (DPD/Cr) was measured as an indicator of osteoclastic activity. BMD was assessed in all children by DEXA screening.
Results: Serum leptin levels and osteocalcin levels were significantly higher in obese children than in the controls (both p<0.001). The urine DPD/Cr in the group of obese children was significantly lower than that in the control group (p<0.001). BMD in obese children was also higher than that in the controls (p<0.001). No significant differences in serum leptin levels, osteocalcin levels and urine DPD/Crs were observed between obese boys and girls in the study group (p>0.05); however, BMD in obese girls was higher than that in obese boys (p<0.05). Positive correlations were found between serum leptin concentrations, serum osteocalcin concentrations and BMD values in obese children (p<0.05). .
Discussion: In the present study, we identified an increase in BMD and serum osteocalcin levels in obese children. Accordingly, such an increase in osteoblastic activity is considered to be associated with an increase in serum leptin levels. More comprehensive studies are required to assess the central and peripheral effects of leptin on bone metabolism.