Impact of Body Fat Mass on Bone Mineral Density and Content and on Serum Level ofc-Terminal Telopeptide of Type 1 Collagen among Overweight and Obese Children andAdolescents

摘要

Background: There is still gap of knowledge about the effect of overweight and obesity on bone mineral density (BMD) and bone mineral content (BMC) during growth. Studies using Dual-energy X-ray absorptiometry (DEXA) to examine the effect of obesity on bone mass in children and adolescents have conflicting results. Aim of the work: was to evaluate the effect of body fat mass on BMD and BMC as well as on the serum level of CTX1 in overweight and obese children and adolescents. Subjects and Methods: This case-control study was conducted on 60 overweight and obese children and adolescents (cases) and 25 age and sex matched subjects with BMI between 15th - < 85th percentiles as controls. The enrolled patients were subjected to the obesity sheet and anthropometric measurements. Assessment of body composition, BMD and BMC of Whole body & A-P spine by DEXA scan and measurement of serum CTX1 by ELISA were performed for cases and controls. Results: The cases had significantly higher mean values of BMD, BMC and lean and fat masses of the whole body, trunk and abdomen than controls. However, no significant statistical differences were found between cases and control as regards the mean values of L2-4 z-score of BMD and BMC. There were no significant correlations between each of peripheral and central fats and z-score L2-4. However, there were significant positive correlations between both BMD and BMC of L2-4 and the whole body and each of BMI, waist and hip circumferences, peripheral and central fat as well as all DEXA parameters. The mean value of serum CTX1 was significantly higher among cases than controls. Meanwhile, there was a significant positive correlation between CTX1 marker and z score of BMI for age and a significant positive correlation between mean values of CTX marker and FemurBMD, whereas Femur BMC and z score as well as Spine BMD, BMC and z score showed no significant correlation with the mean values of CTX1. Conclusion: We concluded that BMD and BMC are increased with the increase in body fat mass. Further, we found that obesity increases the level of CTX1 marker in serum due to greater growth velocity and greater weight bearing in heavier children and adolescents. Therefore, the use of CTX1 as a marker of BMD and bone resorption is not recommended in obese children and adolescents.