Cortisol, also known as hydrocortisone or compound F, is a steroid hormone, in the glucocorticoid class of hormones. It is produced in humans by the zona fasciculata of the adrenal cortex within the adrenal gland. It is released in response to stress and low blood-glucose concentration, therefore, cortisol can be used as a biomarker of stress. Production of cortisol follows an ACTH-dependent circadian rhythm, with peak levels in the morning and decreasing levels throughout the day. Cortisol can be measured in many matrices including blood, feces, urine, and saliva. Most serum cortisol (90 – 95 %) is bound to proteins including corticosteroid binding globulin and serum albumin.
Cortisol is involved primarily in metabolic and immunological actions. In the metabolic aspect, it promotes gluconeogenesis, liver glycogen deposition, and the reduction of glucose utilization. Immunologically, Cortisol functions as an important anti-inflammatory, and plays a role in hypersensitivity, immunosuppression, and disease resistance. Abnormal Cortisol levels are being tested for correlation with a variety of different conditions, these include: prostate cancer, depression, and schizophrenia. It is already known that an excess of Cortisol in all bodily tissues is the cause of Cushing’s Syndrome.