An assessment of cortisol analysis in hair and its clinical applications

Hair analyses for exogenous compounds, specifically drugs of abuse, have been a useful tool in detecting long-term drug exposure. More recently, studies have delved into the exposure of endogenous compounds in hair. Cortisol is synthesized in the adrenal cortex in response to stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis. While catecholamines generally indicate acute stress, cortisol can be used as an indicator for sub-acute and chronic stress. Studies on the effects of chronic stress are most often subjective in nature, relying on questionnaires asking the participant to recall on past stressors. This can lead to the issue of recall and reporting bias. A new objective measure of chronic stress is needed for a more accurate understanding of the effects of chronic stress on the body. This review uses emerging evidence to describe the usefulness of hair analysis for cortisol and discusses the current methods used.