Hair Cortisol Measurement and Relationships with Growth Among Amazonian Shuar Children

Single page posterCortisol is a hormone secreted by the adrenal gland in response to stress. It is a widely-used biomarker of chronic stress. Measurement of cortisol from hair allows assessment of cumulative concentrations of cortisol, and therefore stress, over a period of months. Hair samples and anthropocentric dimensions, such as height, were collected from Shuar participants (3-19 years old) in Amazonian Ecuador in 2012 to establish reference levels of hair cortisol in Shuar children and examine relationships between cortisol and growth. At least 3 cm of hair was cut from the posterior vertex of the scalp using surgical scissors to represent the prior 3 months of cortisol accumulation given human hair growth of ~1 cm/month. Cortisol was extracted from pulverized hair samples using a modified version of the method of Meyer et al. (2014) and assayed in duplicate using Salimetrics ELISA kits. Thirty-two of 52 Shuar samples has extremely low levels of cortisol. Nineteen of these 32 samples with extremely low levels of cortisol were individuals taller than the average height, whereas those with relatively high levels of cortisol tended to be shorter than those with extremely low levels of cortisol, suggesting a negative association between cortisol levels and height. This research is valuable because it investigates the relationships between a long-term measure of psychosocial stress and growth in a non-Western population. In addition, it describes refinements of an existing method and helps make this technique available to other researchers