Importance of methodological details in the measurement of cortisol in human hair

Objective. The measurement of cortisol in hair became a popular and frequently used methodology in human stress research. This methodological approach, depending on the length of hair analyzed, allows to reflect cortisol secretion over prolong time periods in a retrospective fashion. There is a big variability in the experimental approaches to cortisol extraction used in individual laboratories. Moreover, there are many methodological details which are not described in most of the published papers, although they may be influential. The aim of the present study was to identify and optimize selected methodological steps of hair cortisol extraction.

Methods. As the starting point served the methodology of Xiang et al. (2016). A hair pool was used to test the procedures. The main steps modified were pulverization, methanol extraction and centrifugation.

Results. In the presented procedure, we decreased the speed and duration of the pulverization, we increased the volume of methanol and increased the time and speed of centrifugation. The results showed obtaining lower variability and higher cortisol concentrations than those we obtained by the methodology of Xiang et al. (2016), which was optimized.

Conclusion. The presented methodology is relatively simple and is likely to provide reliable results with low variability of cortisol concentrations measured in the same sample.