Diurnal patterns of salivary cortisol across the adolescent period in healthy females

When examining the diurnal profile of the hormone cortisol in children and adolescents developmental issues are particularly relevant. Previous findings regarding relationships between cortisol secretory activity and reproductive (pubertal) maturation lack clarity and may reflect methodological inconsistencies between studies. This study examined the diurnal cortisol profile across female adolescence, with a particular focus on an obvious and unique marker of development: menarche.
In a cross-sectional design, 61 healthy female adolescents aged 9–18 years (mean age 13.89 years, S.D. ± 2.72) collected eight saliva samples per day on two consecutive weekdays. Samples were collected at awakening, 15, 30 and 45 min and 3, 6, 9 and 12 h post-awakening in order to capture both the cortisol awakening response (CAR) and the subsequent period of decline. Demographic information was recorded and participants also completed the Spielberger State-Trait Anxiety Inventory.
Patterns of cortisol secretion exhibited good intra-individual stability across the two sampling days. Participants evidenced a robust diurnal pattern, with cortisol levels peaking approximately 30–45 min post-awakening (the CAR) and steadily declining concentrations over the remainder of the day. Differences according to developmental status (in terms of whether or not participants had experienced first menses: menarche) were observed in the time of peak secretion of the CAR, and these distinct patterns could not be accounted for by group differences in demographic, situational or psychological characteristics measured in this study. This effect for the CAR was associated with the onset of menarche alone, unlike cortisol levels over the remainder of the day. For those who had undergone menarche, were older and of greater BMI, cortisol levels remained higher over the day. There was a significant difference in cortisol concentrations at 6 h post-awakening between pre- and post-menarche groups. Again, these differences in daytime cortisol secretory activity could not be attributed to situational or psychological factors. Establishing patterns of cortisol secretion in healthy female adolescents provides an important baseline from which to investigate hypothalamic–pituitary–adrenal (HPA) physiology, measured via salivary cortisol, in adolescent populations with known or suspected psychopathology.