Background: Since its discovery in 2012 the browining adipokine irisin is known to lead to increased thermogenesis and energy expenditure. Studies in children are scarce, with results similar to most studies in adults.
Objective and hypotheses: To establish a link between total and abdominal fat mass, physical activity and irisin in preschool age.
Method: Height, weight and waist circumference (WC) of 40 healthy pre-pubertal city children were measured at mean age of 5.31±0.74 years. Normal weight, overweight and obesity were defined by BMI values compared to the age and sex specific CDC2000 reference, while abdominal obesity was defined as WC>90th percentile, according to own published reference. Blood for testing was taken after 12 h of overnight fasting. Children wore pedometers to measure physical activity (PA). A DXA scan was performed to determine and validate abdominal obesity.
Results: With obesity were 17.5% of the participants. Only 9.7% of all met the minimum recommendations for PA during week-days and 16.1% at weekends. Total fat mass (FM) by DXA correlated significantly with BMI and WC (P<0.001). The mean irisin level was 0.95±2.39 μg/ml, withiout significant sex difference (P=0.451). Irisin serum levels correlated with total FM (r=0.406; P=0.039), without significant correlation with BMI or WC. Children with WC>90th percentile had significantly higher values of irisin (P=0.025). Irisin levels were also higher in children, covering minimum requirements for PA (at least 10 000 steps per day). When analyzing the factors with a potential influence on serum concentrations of irisin (age, sex, indicators of obesity, body composition, PA), only WC proves to have a positive significant effect (β=1.333; P=0.025).
Conclusion: This study finds a significant association between total fat mass, abdominal fat, waist circumference and irisin in healthy children. Irisin is definitely an interesting biomarker for studing the interrelations between fat mass and muscle.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology