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

Introduction: 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. Aim of the study: To estimate salivary cortisol concentrations in healthy school-aged children and relate the concentrations to age, sex, stage of puberty and adult values. Patients and method. 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 -20degreesC 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. Conclusion: 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.