Cortisol is a corticosteroid hormone or glucocorticoid produced by the zona fasciculata of the adrenal cortex. Diagnosis of adrenocortical insufficiency  helps diagnose Addison disease, adrenocortical hyperseretion, and Cushing syndrome. This test is also used to diagnose malfunction in the hypothalamic-pituitary-adrenal cortex axis.

Special Instrustions:  Blood must be drawn at 8AM and 4PM to establish a baseline.