Cortisol is released by the adrenal gland following the stimulation by ACTH (adrenocorticotropic hormone) which is produced by the anterior pituitary gland. This gland is itself triggered by corticotropin-releasing hormone produced by the hypothalamus. The process is called the hypothalamus-pituitary-adrenal (HPA) axis.

Measurement of cortisol can be done in saliva, blood and urine. These matrices reflect current levels in the body. Long term levels as measured in hair may allow assessments relating to causation of chronic diseases based on a continuous activation of the HPA axis.

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