Revisiting the cortisol reference ranges in humans: the role of demographics

The current study explores the effect of demographics on serum cortisol expression in a study group of 52 individuals to improve the current serum reference ranges to produce personalized expression profiles consequently increasing clinical confidence in the diagnosis. The serum cortisol concentration was inspected against demographical data like age, sex, and body mass index and showed an association with age and sex. The serum cortisol values also indicated a positive association with chronic illnesses however this finding requires a more focused study for establishment. Additionally, saliva samples are also collected from the same study group at the same time through drool and an absorbent sponge and correlated with serum values to draw an alternative route of serological testing. Salivary cortisol from drool showed a linear correlation with Pearson's correlation coefficients of 0.71 and 0.72 with serum cortisol and with saliva samples collected using a porous sponge respectively. Overall, the study shows the role of demographics in shaping the reference ranges for cortisol, suggesting a path for developing personalized diagnostics. The study also highlights the efficacy of saliva as an alternative to serum cortisol to facilitate cortisol measurement for efficient stress management.