Body Composition Changes, Bone Density and Bone Turnover Markers in Obese Children

Abstract

Background: Osteoporosis is a major health problem.Itis a disease of progressive bone loss associated with increased risk of fractures.A dramatic increase in prevalence of pediatric obesity has occurred in most countries over the past few decades.Understanding the relationship between pediatric obesity and bone health is relevant for health professionals, because childhood and adolescence are two critical periods in the prevention and development of diseases in adulthood. Aim: This study aimed to study the relation between obesity, body composition and bone density by using dual energy x-ray absorptiometry (DEXA) and some bone turnover markers as Osteocalcin (OC) and Deoxypyridinoline (DPD) in obese children. Design: Case-control study. Methods: a case-control sample of 80 pre-pubertal, Egyptian children aged 6-10 years were divided into 40 cases with simple obesity (BMI ≥ 95th percentile) and 40 controls (non-obese). Physical examination that included weight, height, hip circumference and waist circumference were performed. Body mass index (BMI) and waist-hip ratio were calculated. Blood and urine samples were collected. Serum was separated and assayed for Osteocalcin, calcium, phosphorus, alkaline phosphatase and lipid profile. Urine was collected, centrifuged and assayed for deoxypyridinoline. Results: All anthropometric parameters were increased (except for height) in obese children. All DEXA parameters for the whole body, hip and lumbar areas were greater in obese children. All DEXA parameters for the whole body were positively correlated with BMI, weight and height. Lipid profile was positively correlated with most of DEXA parameters as area, BMD, total body fat, lean, lean + BMC and total mass but they were negatively correlated with high density lipoprotein (HDL). Calcium showed significant increase in obese children, while alkaline phosphatase showed significant decrease in the same group. Osteocalcin was found to be negatively correlated with most of DEXA results in obese children in comparison to non-obese children. While the urinary DPD, showed no significant difference between obese and non-obese groups. Conclusion: obese children have increased anthropometric and DEXA parameters which were positively correlated with BMI, weight, height and lipid profile except for HDL. Obese children also showed significant increase in serum calcium and significant decrease in alkaline phosphatase. Osteocalcin was found to be negatively correlated with most of DEXA results in obese children in comparison to non-obese children. While the urinary DPD, showed no significant difference between obese and non-obese groups. Recommendations: we recommend the childcare providers to supply the children with healthy balanced diet to avoid obesity throughout their life with the use of DEXA and Osteocalcin as early predictors of osteoporosis in obese children to avoid continuation of the problem of osteoporosis in the adulthood, while for the urinary DPD, as it did not give us any significant data either in obese or non-obese children in addition to its high price, so we do not recommend its use in this early age.

Keywords: Osteoporosis, obese children, bone markers, dual energy x-ray absorptiometry (DEXA).