A cortisol level test uses a blood sample to measure the level of cortisol present in your blood.
Cortisol is a steroid hormone released by the adrenal glands. The adrenal glands sit on top of your kidneys. A cortisol level test may also be called a serum cortisol test.
The cortisol level test is used to check if your cortisol production levels are either too high or too low. There are certain diseases, such as Addison’s disease and Cushing’s disease, which affect the amount of cortisol your adrenal glands produce.
When assessed with a typical radioimmunoassay (the most commonly used method), cortisol levels range from about 10 to 20 micrograms per deciliter (ug/dl) in the early morning (within one hour of the usual time of awakening), from 3 to 10 ug/dl at 4 PM, and are usually less than 5 ug/dl after the usual bedtime
