ESPE Abstracts

Background: Obesity has been associated with perturbations of the hypothalamic–pituitary–adrenal (HPA) axis and the sympathetic nervous system (SNS). Scalp hair cortisol has been recognized as a reliable index of long-term cortisol concentrations.

Objective and hypotheses: Aim of this study was to compare indices of HPA axis and SNS activities, such as, respectively, the salivary cortisol and alpha-amylase diurnal patterns, and their relations in obese and normal weight prepubertal girls. Furthermore, we compared cortisol concentrations in scalp hair between groups and investigated whether they are correlated with salivary cortisol concentrations.

Method: Five saliva samples were collected serially over a weekend day (at 9:00, 12:00, 15:00, 18:00, 21:00 hours) from 26 obese (mean age 7.4±1.3 years, BMI 24.6±3.3 kg/m²) and 24 normal weight prepubertal girls (mean age 7.8±1.1 years, BMI 16.9±1.6 kg/m²). Cortisol and alpha-amylase concentrations were measured and areas under the curve (AUCs) were calculated. We investigated cortisol and alpha-amylase linear correlations in each group. Hair samples from the posterior vertex of the scalp were collected and analysed for cortisol.

Results: Positive linear correlations between hair cortisol and both BMI z-score and salivary cortisol AUC were found (P<0.05). In obese girls, significantly higher salivary and hair cortisol concentrations were observed compared to normal weight girls (P<0.05). Inversely, salivary alpha-amylase AUC was significantly lower in the same group (P<0.05) and a negative linear correlation between cortisol and alpha-amylase was observed (P<0.05).

Conclusion: Obese prepubertal girls demonstrated changes in both salivary cortisol and alpha-amylase diurnal secretions compared to normal weight controls, suggesting altered stress system function in the obese group. Increased hair cortisol concentrations and positive correlations with salivary measurements suggest chronic stress-related activation of the HPA axis in obese girls. Hair cortisol appears to be a sensitive measure of hypercortisolism in obesity.