Cortisol is a steroid hormone produced by the adrenal fascicular zone of the adrenal cortex. It belongs to the group of corticoids and makes up approximately 75-90% of all corticosteroids circulating in the blood.

How cortisol secretion is regulated:

• Adrenocorticotropic hormone (ACTH): is secreted by the anterior pituitary gland and stimulates the production of cortisol.
• Binding in the blood: most cortisol circulates in the blood in a protein-bound form.
• Metabolism: cortisol is broken down (metabolized) mainly in the liver.