Assessment of hair cortisol in euthyroid, hypothyroid, and subclinical hypothyroid subjects.

Abstract

Hypothyroidism is associated with an increase in serum cortisol level while the long-term activity of hypothalamic-pituitary-adrenal (HPA) axis in hypothyroid, and subclinical hypothyroid (SCH) subjects has not been studied. This study aimed to assess the hair cortisol levels as a long-term activity of HPA axis in hypothyroid, SCH and a group of healthy adult subjects. Also, it aimed to examine the correlation of hair cortisol levels with hypothalamic-pituitary-thyroid (HPT) axis and anthropometric measures. We prospectively evaluated a group of normal, SCH and hypothyroid subjects. Serum TSH, FT4, and FT3 were measured as a component of the HPT axis. Hair samples were collected, prepared, followed by extraction of hair cortisol and measurement in pg/mg of hair. Hair cortisol levels were compared in normal, SCH and hypothyroid groups and correlated with HPT axis and anthropometric data. A total of 65 healthy volunteers were analyzed, and the mean hair cortisol level was reported to be 17.38 pg/mg of hair. Hair cortisol level was slightly higher in the SCH subjects, 18.19 pg/mg of hair; however the difference was not significant. Compared to the euthyroid subject, a significantly higher hair cortisol level was recorded in the hypothyroid subjects, 24.17 pg/mg hair, p < .05. Hair cortisol was significantly and positively associated with each of the serum TSH, age, weight and BMI (p < .05). Overt hypothyroidism but not SCH is significantly associated with higher hair cortisol levels compared to normal subjects, and a significant relation between hair cortisol with HPT axis was found. Also, weight and BMI were positively correlated with hair cortisol level.