Measuring cortisol and DHEA in fingernails: A pilot study

Fay Warnock¹, Kevin McElwee², Rubo J Seo³, Sean McIsaac³, Danielle Seim³, Tatiana Ramirez-Aponte³, Karine AN Macritchie³, Allan H Young³

¹Developmental Neuroscience and Child Health, BC Children’s Hospital, Vancouver, BC, Canada; ²Department of Dermatology and Skin Science, ³Institute of Mental Health-Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada

Purpose: Abnormalities in both cortisol and dehydroepiandrosterone (DHEA) have been reported in psychiatric disorders. Analysis of saliva, urine and blood cortisol and DHEA levels provides an index of hormone levels over a short time period. Unlike such conventional measures, fingernails incorporate endogenous hormones that passively diffuse to the nail matrix from capillaries during keratinization. This study piloted the measurement of cortisol and DHEA levels in fingernails as a potential measure of their accumulated secretion of steroid hormones over a prolonged time period.

Method: Thirty-three university students (18–24 years) provided fingernail samples on two occasions over a school semester. The visits were scheduled so nail cortisol and DHEA levels were collected from periods when students might be under different levels of stress.

Results: During the putatively stressful period, the nail samples showed a significant increase in the cortisol: DHEA ratio (P = 0.0002) due to a significant decrease in the DHEA levels (P = 0.004) and a numerical but not statistically significant increase in the cortisol levels (P = 0.256).

Discussion: This pilot study showed that nails can be used to measure cortisol and DHEA, a measure which may reflect environmental stress. More work is required to further validate this technique which may prove useful in studies of both healthy individuals and patient groups.

Keywords: stress, nails, cortisol, DHEA