Sex-related differences in the association of ghrelin levels with obesity in adolescents

Background: The utility of ghrelin as a biomarker may be different depending on gender. The aim of this study was to assess ghrelin levels in a population-based sample of adolescents, and to evaluate their association with obesity and obesity-related parameters depending on sex. Methods: The studied population included 601 randomly selected 14- to 16-year-old children. Anthropometrical data were measured and body mass index (BMI) and waist to hip ratio calculated. Body composition was assessed using an impedance body composition analyzer. Total serum ghrelin levels were determined using a multiplexed bead immunoassay. Serum leptin and adiponectin levels were determined by ELISA and insulin by RIA. Results: Ghrelin levels were significantly higher in girls than in boys. Serum ghrelin concentrations were significantly lower (p<0.01) in obese than in normal weight (NW) girls, but showed no differences by weight category in boys. Ghrelin showed a significant negative relationship with waist circumference (WC), waist to hip ratio and fat mass (p<0.05) in both genders, and with weight and BMI (p<0.01) in girls, and insulin (p<0.01) and HOMA (p<0.05) in boys. Ghrelin also correlated negatively with leptin levels in girls (p<0.01). Conclusions: Our study describes serum ghrelin levels in adolescents, showing a sexual dimorphism in ghrelin levels in these 14- to 16-year-old children, and a different association of ghrelin levels with obesity by gender that suggests a different appetite and energy expenditure control depending on sex at this age.