Increased scalp hair cortisol concentrations in obese children.

Pathologically increased cortisol exposure induces obesity, but it is not known whether relatively high cortisol within the physiological range is related to childhood obesity. The aim of the study was to compare hair cortisol concentrations between obese and normal-weight children. We performed an observational case-control study. Twenty obese children (body mass index-SD score [BMI-SDS]>2.3) and 20 age- and sex-matched normal-weight children (BMI-SDS<1.1) aged 8-12 years were recruited. Scalp hair samples from the posterior vertex were collected, and hair cortisol concentrations were measured using ELISA. Body weight, height, and waist circumference were measured. From the obese children, additional data on blood pressure and blood lipid concentrations were collected. In both groups, five boys and 15 girls were included; their mean age was 10.8±1.3 vs 10.8±1.2 years (obese vs normal weight; not significant). Body weight, BMI, BMI-SDS, and waist circumference were higher in the obese children compared with the normal-weight children (69.8±17.2 vs 35.5±7.2 kg; 29.6±4.9 vs 16.4±1.6 kg/m2; 3.4±0.5 vs -0.2±0.8 SDS; 94±13 vs 62±6 cm; P<.001 all). Hair cortisol concentration was higher in obese than normal-weight children (median [interquartile range], 25 [17, 32] vs 17 [13, 21] pg/mg; P<.05). Hair cortisol concentration, a measure for long-term cortisol exposure, was higher in obese children than normal-weight children. This suggests long-term activation of the hypothalamus-pituitary-adrenal axis in obese children and may provide a novel target for treatment of obesity in children.