The Significance of Hair Cortisol Analysis in Clinical Practice and Research

Cortisol is the main glucocorticoid synthesized from cholesterol in adrenal zona fasciculata cells. Nonspecific stimuli such as physical or psychological stress results in hypothalamic-pituitatary-adrenal (HPA) axis activation and secretion of cortisol which has a wide spectrum of biological effects. Therefore, different diagnostic tests are used to evaluate HPA axis activity in routine clinical practice, e.g. dexamethasone suppression test, determination of adrecorticotropic hormone (ACTH) in blood serum and cortisol concentration measurement in both blood serum and 24-hour urine samples. However, these measurement strategies reflect only momentary or short-term cortisol secretion but cannot provide the information about long-term int egrated cortisol exposure. In this context, there is a growing number of evidence that endogenous cortisol concentrations can be measured in scalp hair which has a unique property to incorporate steroid hormones and other lipophilic substances into growing hair. It was showed that determination of hair cortisol concentration is a promising tool for Cushing’s syndrome diagnostics, hydrocortisone replacement therapy monitoring, cardiometabolic status assessment and chronic stress evaluation. Despite a lot of scientific effort put into hair cortisol research, data about the other factors which could affect the results of hair testing such as hair growth rate, hair colour, gender, age, ethnic group is insufficient. Also, the use of various hair sample preparation procedures and analytical methods becomes a challenge for assay standardisation, implementation in clinical practice and comparison of findings from different studies. The main purpose of this article is to review the importance of hair cortisol concentration measurements, the possibility of adopting this test in clinical practice and research, and to report different methods for quantitative hair cortisol analysis.