Hair Cortisol | UCSF SMN

The stress hormone cortisol, secreted mainly from the adrenal gland, can be measured in various matrices, including blood, saliva, urine, and more recently hair. The method of choice depends on the time window of interest and the research question.

The stress hormone cortisol, secreted mainly from the adrenal gland, can be measured in various matrices, including blood, saliva, urine, and more recently hair. The method of choice depends on the time window of interest and the research question. Plasma and salivary cortisol samples reflect “snapshots" of recent hypothalamic pituitary adrenal (HPA) axis activity, reflecting cortisol activity over seconds to minutes prior to collection. Urinary cortisol samples provide insight into the time window of collection ranging from overnight to 24-hour periods. In contrast, hair cortisol provides a window on longer-term (months) cortisol exposure levels. Here we focus on hair cortisol, as a measure of long-term HPA activity that is relatively easy to implement in field and population-based studies of aging.

Assessment of cortisol in hair is a recent method that quantifies cumulative cortisol production over extended periods of time (up to 6 months), suggesting that hair cortisol may be a unique biomarker of long-term HPA axis activity. Cortisol is incorporated into the hair as it grows (Pragst & Balíková, 2006) and measurement of cortisol levels within a specific hair segment reflects integrated, cumulative cortisol secretion within that hair growth period. Scalp hair growth is variable, but an average rate of 1 cm per month has been generally accepted (Harkey, 1993; Pragst & Balíková, 2006; Wennig, 2000). Thus, a proximal (scalp-close) 1–cm hair segment reflects total cortisol secretion in the last month, the second proximal 1–cm segment represents the cortisol production in the month before that and so on. Several studies have validated hair cortisol measurement, linking hair cortisol concentrations to repeated measures in saliva and urine, and studying hair cortisol concentrations in patients with endocrine disorders, such as hyper- or hypocortisolism (for reviews see Gow, Thomson, Rieder, Van Uum, & Koren, 2010; Russell, Koren, Rieder, & Van Uum, 2012). Hair cortisol has also been linked to chronic stress exposures and mental health conditions (Stalder et al., 2017; Staufenbiel, Penninx, Spijker, Elzinga, & van Rossum, 2013). It is higher in pregnancy, as expected (Kirschbaum, Tietze, Skoluda, & Dettenborn, 2009). It can be measured in newborns and may be lower in newborns with preterm birth (Hoffman, D'Anna-Hernandez, Benitez, Ross, & Laudenslager, 2017).

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