Low ghrelin level affects bone biomarkers in childhood obesity

Obesity not only compromises linear growth but also affects bone mineralization. It was reported that ghrelin, which is an orexigenic hormone, affects bone metabolism. This study was designed to estimate ghrelin level in 20 obese children in comparison with 12 healthy age- and sex-matched controls and to assess the hypothesis of ghrelin influence on biochemical markers of bone turnover. The enrolled children were subjected to detailed history taking and thorough clinical examination as well as determination of bone age. Laboratory investigations were done including estimation of total serum ghrelin, serum osteocalcin, and parathyroid hormone (PTH). Obese children showed significantly higher anthropometric measurements compared to the controls and higher bone age compared to their chronological age. There were significantly lower total serum ghrelin and serum osteocalcin and significantly higher serum PTH in obese children compared to the controls (P < .001, respectively). Significant negative correlations were detected between each of serum ghrelin and the body mass index percentage as well as the sum of skin fold thicknesses (P < .001 and P < .01 respectively). In addition, the current study demonstrated a significant positive correlation between the serum ghrelin and serum osteocalcin (P < .01) and a significant negative correlation between serum ghrelin and serum PTH (P < .001). In conclusion, the low ghrelin levels in obesity might be the cause for the decreased bone density reported in such condition. Trials for ghrelin administration could thus be justified to help obese individuals maintain their normal bone density till this is replaced or augmented by the physiological rise reported on weight reduction.