It is the primary glucocorticoid produced and secreted by the adrenal cortex.
Serum levels are highest in the early morning and decrease throughout the day.
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, additionally, plays a role in hypersensitivity, immunosuppression, and disease resistance. Factors such as age, various diseases, nutrition, and other hormone levels affect cortisol secretion. It has also been shown that plasma cortisol levels elevate in response to stress.