Wednesday, 17 August 2016

A Cortisol Study; Facial Hair and Nails

In recent years, the scientific community's interest in stress related cortisol has increased dramatically, along with the stresses of Westernized day-to day life. The effects of prolonged exposure to stress in our daily routines results in what we call allostatic load. When there is an increase in the allostatic load, it can result in receptor desensitization, tissue damage, and other physical and mental maladies. For these reasons and more, it is of vital importance to accurately measure short term cortisol levels caused by both mental and physical stress.

cortisol research journals

Under conditions of physical and psychological stress  the cortisol hormone is released by the zona fasciculate of the adrenal cortex in the kidneys and periphery- which is stimulated by an HPA-like axis (Hypothalamus Pituitary Axis) within the hair follicle. Moreover, it is well documented that blood-borne substances are able to diffuse from capillaries into the cells of hair follicles and subsequently become deposited into the hair shaft and fingernails.

Recently  it has been hypothesized that cortisol is incorporated into both hair and nails via similar cellular mechanisms. In this study, we build upon this hypothesis, theorizing that cortisol within facial hair is incorporated in the same fashion. Saliva and serum cortisol levels are subject to major physiological circadian fluctuations. Additionally, the collection method used with these mediums is invasive and costly. Alternatively, hair and nail analysis presents a longer history of cortisol levels, as well as a non-invasive, cost effective means of collecting samples.


A pilot study by Warnock et al.was the first to find cortisol in finger nails. The data showed the feasibility of cortisol assessment in fingernails and significant correlations between cortisol and DHEA in subjects. A follow-up study done by Izawa et al.confirmed these results. Yet, to date, no existing study has investigated potential variations in cortisol levels between fingernails and toenails.

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