Interrelationships between Sarcopenia, Bone Mass, and Metabolic Parameters in Pediatric Obesity

Introduction: Sarcopenic obesity (SO) is defined as co-existence of obesity and sarcopenia. The co-occurrence of sarcopenia and obesity might act synergistically and SO might have a greater effect on adverse health outcomes than sarcopenia or obesity alone. The term osteosarcopenic obesity was introduced recently to describe the impairment of bone, muscle, and fat tissues. This study aimed to evaluate cardiometabolic and bone parameters in relation with the presence of sarcopenia and their association with components of sarcopenia (muscle strength, muscle mass, and physical performance) in children and adolescents with obesity.

A total of 95 children and adolescents with obesity (diagnosed with the use of International Obesity Task Force criteria) with a mean age of 12.7(±3) years participated in this study. Body composition was evaluated by bioelectrical impedance (BIA) and dual-energy X-ray absorptiometry (DXA). Grip strength and physical performance (six-minute walk test, timed up and go test) were evaluated. Blood pressure was measured and blood samples were taken. Sarcopenia was defined as co-occurrence of weak handgrip strength (≤10th centile) according to Dodds et al. [PLoS One. 2014;9(12):e113637] and low DXA-ASMM% (appendicular muscle mass/weight × 100%) (≤9nd centile) according to McCarthy et al. [Pediatr Obes. 2014;9(4):249-59].

The overall prevalence of sarcopenia was 17.89%. In comparison with patients without sarcopenia, those with sarcopenia had significantly higher high-density lipoprotein cholesterol (HDL-C) and significantly lower total body less head bone mineral content (BMC-TBLH) and total body less head bone mineral density (BMD-TBLH). Partial correlation analyses controlling for age and sex were performed. BIA-ASMM% and DXA-ASMM% were negatively correlated with insulin 0', homeostasis model assessment of insulin resistance (HOMA-IR) and diastolic blood pressure. DXA-ASMM% correlated negatively with total cholesterol. Handgrip strength was negatively correlated with total cholesterol, low-density lipoprotein (LDL), and HDL cholesterol. Maximal handgrip was positively correlated with bone parameters (BMC-TBLH, BMC-lumbar spine (LS), BMD-TBLH, and BMD-LS). The highest diagnostic value for detecting sarcopenia in children and adolescents with obesity was achieved by HDL-C (cut-off value >44.8 mg/dL), area under ROC curve (AUC) = 0.73).

Muscle mass and muscle strength were significantly associated with cardiometabolic parameters in children and adolescents with obesity. The best independent predictive risk factor for diagnosing sarcopenia in obese children and adolescents is HDL-C (cut-off value >44.8 mg/dL). The results of our study regarding bone parameters suggest the presence of osteosarcopenic obesity.