Salivary but not blood cortisol excretion is associated with metabolic biomarkers in healthy young women.

OBJECTIVES: Elevated and suppressed concentrations of cortisol have been linked with less favorable metabolic biomarkers, such as elevated lipids and glycosylated hemoglobin (HbA1c). Based on recent work reporting that some individuals secrete more cortisol into saliva (high saliva-to-blood cortisol ratio; high secretors) than others after correcting for blood cortisol concentrations, our objectives were to examine (1) whether lipids and glycosylated hemoglobin varied across cortisol and salivary secretor status; and (2) if blood and saliva provide the same results with respect to metabolic markers.

METHODS: Matched saliva and dried blood spot (DBS) specimens collected once a week for four weeks (N = 48 healthy women, 192 specimens) were assayed for cortisol. Fasting blood specimens collected once from each woman were quantified for cholesterol (total, HDL, LDL), triglycerides and HbA1c.

RESULTS: Low salivary cortisol secretors showed significantly higher triglyceride and HbA1c compared to high-secretors (P<0.05; t-test). The only significant correlation with mean blood or salivary cortisol concentration was a negative correlation between salivary cortisol and HbA1c (P = 0.021, r = -0.333).

CONCLUSIONS: Triglycerides, HDL, and especially HbA1c were associated with salivary cortisol secretor status but not with DBS cortisol concentrations. These results suggest that blood and saliva cortisol measures might provide different health outcome information, and that salivary cortisol secretor status may provide additional information on health status. Am. J. Hum. Biol. 28:539-544, 2016. © 2016 Wiley Periodicals, Inc.