The effect of hypothalamic-pituitary-adrenal axis activity on bmi of preschool children

The effect of Hypothalamic-Pituitary-Adrenal Axis Activity on BMI of Preschool Children Aim: Stress is an integral part of our daily life. The effect of stress on growth and body mass index (BMI) is a known fact. Cortisol, the stress hormone, is produced by the hypothalamo-hypophyseal-adrenal (HHA) axis and has known effects on growth. In this study, BMI and salivary cortisol levels were compared in 3 to 6 year-old pre school children. Method: This study included 288 children (120 girls and 168 boys) aged between 3 and 6 who had received pre-school education in Zübeyde Hanım Kindergarten in the Palandöken district of Erzurum province. Of girls, 75 were morning attendants and 45 were afternoon attendants; of boys, 105 were morning attendants and 63 were afternoon attendants. Three saliva samples were taken from children on each of the three consecutive days: one sample was taken at home within 30 min post-awakening and the other two samples were taken in the school at the end of first and third lessons. Cortisol levels measured in saliva samples were compared with BMI. Cortisol levels were assessed by using a validated ELISA method and the data were analyzed using the MINITAB (USA) statistical program. Results: Cortisol levels were the highest post-awakening and dropped thereafter during the first and third lessons (P<0.001). Therefore, the data obtained show that the cortisol awakening response (CAR) also occur in the pre-school children and cortisol levels decrease with the progress of the day. There were no difference between the days in terms of CAR (P>0.05). Although early morning samples were similar, levels of cortisol in lesson 1 and 3 were higher in boys (P<0.01 and P<0.001, respectively). CAR was lower or blunted in the children with low BMI than the other children (P <0.001). Conclusions: With normal BMI in this study, CAR was observed in pre-school children except those with lower BMI. This suggests that lower BMI in pre-school children is associated with dysfunctioning HHA axis and this, in turn, might have important pathophysiological consequences. Key Words: Saliva, cortisol, BMI, pre-school children