The main hormone involved in stress and the “fight or flight” response. This response is a natural and protective response to a perceived threat or danger. It is done to measure the level of the hormone cortisol in the blood.
Guide. A cortisol test is done to measure the level of the hormone cortisol in the blood. The cortisol level may show problems with the adrenal glands or pituitary gland. Cortisol is made by the adrenal glands. Cortisol levels go up when the pituitary gland releases another hormone called adrenocorticotropic hormone (ACTH).  Cortisol is a steroid hormone made in the adrenal glands. Cortisol's important function in the body includes roles in the regulation of blood pressure and cardiovascular function as well as regulation of the body's use of proteins, carbohydrates, and fats. Stress is the sum total of all mental and physical input over a given period of time. The marker used to measure stress is the adrenal steroid hormone, cortisol. Stress, whether physical or emotional in origin, provokes a response by Cortisol is a steroid hormone produced by the adrenal gland. It is released in response to ACTH (adrenocorticotropic hormone), which is produced by the pituitary gland near the brain. Adrenocorticotropic hormone stimulates the secretion of hormones by the adrenal cortex. Cortisol is the main hormone involved in stress and the “fight or flight” response. This response is a natural and protective response to a perceived threat or danger. Overview. A cortisol level test uses a blood sample to measure the level of cortisol present in blood. Cortisol is a steroid hormone released by the adrenal gland. The adrenal glands sit atop the kidneys. A cortisol level test may also be called a serum cortisol test. Cortisol is the main hormone involved in stress and the “fight or flight” response. This response is a natural and protective response to a perceived threat or danger. Your adrenal glands are responsible for all of your responses to stress. Levels of the main adrenal hormone, cortisol, rise and fall in a daily pattern that underlies the more erratic fluctuations caused by the stress response. Cortisol output by your adrenal glands is one of the most reliable indicators of your adrenal function and how well your body is dealing with stress. Yes, saliva tests are reliable indicators of the levels of all steroid hormones (cortisol, DHEAS and all sex steroids) in your body. However just as with blood tests, some labs are more reliable than others – especially for sex steroids, like estrogens. 1 Blood/Serum. 2  A cortisol test is done to measure the level of the hormone cortisol in the blood, which may indicate problems with the adrenal glands or pituitary gland. 3  Ideally, perform the test around 8:00 a.m., and aim for the optimal range for adults of 10-15 mcg/dL. When it comes to cortisol testing, here are the best options. 1  Blood/Serum. 2  A cortisol test is done to measure the level of the hormone cortisol in the blood, which may indicate problems with the adrenal glands or pituitary gland. Testing for Excess Cortisol Production. If a person has a high blood cortisol level, a health practitioner may perform additional testing to confirm that the high cortisol is truly abnormal (and not simply due to increased stress or the use of cortisol-like medication). Cortisol is produced and secreted by the adrenal glands. Production of the hormone is regulated by the hypothalamus in the brain and by the pituitary gland, a tiny organ located below the brain. Description. Cortisol is the main adrenal glucocorticoid and plays a central role in glucose metabolism and in the body's response to stress. Adrenal cortisol production is regulated by adrenocorticotropic hormone (ACTH), which is synthesized by the pituitary gland in response to hypothalamic corticotropin-releasing hormone (CRH). 
http://www.webmd.com/a-to-z-guides/cortisol-14668 https://www.directlabs.com/Resources/Hormones/StressHormones.aspx http://www.healthline.com/health/cortisol-urine http://www.healthline.com/health/cortisol-urine https://adrenalfatigue.org/saliva-testing-for-adrenal-hormones/ http://www.saragottfriedmd.com/cortisol-testing/ https://labtestsonline.org/understanding/analytes/cortisol/tab/test http://emedicine.medscape.com/article/2088826-overview
what is involved in a cortisol test