Hair Cortisol and Chronic Stress

Hair Cortisol and Chronic Stress

Yamada J, Stevens B, de Silva N. et al: Hair Cortisol as a Potential Biologic Marker of Chronic Stress in Hospitalized Neonates. Neonatology 2007;92:42–49 Article (References) Article (PDF 183 KB)

Objectives.To determine whether (a) hair cortisol levels differed between term and preterm infants exposed to stress in the NICU and (b) an association exists between hair cortisol levels and severity of illness or indicators of acute stress.

Methods. Hair cortisol levels were determined using the ELISA method (solid-phase enzyme-linked immunoassay, Alpco Diagnostics, Windham, N.H., USA) in 60 infants > 25 weeks gestational age at birth.

Results. No significant differences were found between the hair cortisol levels of term infants compared to preterm infants in the NICU. When compared to a group of healthy term infants, hospitalized infants had significantly higher hair cortisol levels (t (76) =2.755, p = 0.004). A subgroup analysis of the term NICU infants showed a statistically significant association between total number of ventilator days and hair cortisol levels. For every extra day on the ventilator, hair cortisol levels increased on average by 0.2 nmol/g (p = 0.03). 21% of the variance in hair cortisol levels was explained by the total number of days on the ventilator.

Conclusions: Hair cortisol is influenced by days of ventilation in NICU term infants. This is a potentially valid outcome for chronic neonatal stress in these infants and warrants further investigation.

Comments. Cortisol is a stress hormone and its measurement in the body fluid represents its level over a short period of time thus cannot provide an index of long-term cortisol exposure. In contrast, hair as a matrix for long-lasting analyte exposure can provide the unique opportunity to assess a retrospective calendar of an individual's cortisol exposure over several months. This study showed that neonates admitted to the NICU had significantly higher hair cortisol levels in comparison to a group of healthy full term infants and its level correlates with number of days on mechanical ventilation. A significant number of mothers (37%) had received betamethasone during pregnancy due to threatened preterm delivery and six (10%) infants were given dexamethasone postnatally which might affect the reliability of the endogenous cortisol detection in human scalp hair. In this study a baseline measurement of hair cortisol was not performed and it will be very helpful if it was done to follow the trend of increasing cortisol level in correlation with the level of stress. I agree with the authors that we need more studies to explore this method further and to establish correlations with short and long term outcome. SAA

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