Reference values for morning salivary cortisol concentrations in healthy school-aged children.

Background: In children, sensitive, specific, pain-free sampling methods are important. An alternative is salivary sampling. Our knowledge about steroid levels in saliva and plasma in school-aged children and during puberty is sparse and contradictory.

Objective: To estimate salivary cortisol concentrations in healthy school-aged children and relate the concentrations to age, sex, stage of puberty and adult values.

Methods: Saliva was collected in Salivette tubes from 210 boys and 176 girls aged 7-15 years, and from four adults, between 08.00 and 09.00 h. The tubes were centrifuged and then frozen at -20 degrees C until analysed by a commercial RIA-cortisol kit.

Results: Salivary cortisol was measurable in all infants. Boys and girls had nearly the same median concentrations, 8.8 versus 8.6 nmol/l, but girls had a higher maximal level, 53.9 compared to 33.2 nmol/l in boys. The median concentration was lower in 7-9 year-old children, 7.2 in boys and 5.7 nmol/l in girls, compared to 10-12 year-old children, 11.5 in boys and 10.9 nmol/l in girls (p <0.001). The median concentrations in most age groups were lower than in adults. Salivary cortisol concentration was dependent on stage of puberty.

Conclusions: Salivary cortisol was measurable in the morning in school-aged children and the median concentration was dependent on age, stage of puberty, but not on sex.