A cortisol test measures the level of cortisol in your blood, urine (pee), or saliva (spit). Cortisol is a hormone made by your adrenal glands, two small glands that sit above your kidneys. Hormones are chemical messengers in your bloodstream that control the actions of certain cells or organs. Cortisol affects almost every organ and tissue in your body.

Source: MedlinePlus, U.S. National Library of Medicine