What are cortisol levels?

Cortisol levels indicate how much of the hormone cortisol is in a person's blood, WebMD reports. Doctors test for cortisol levels to reveal potential issues with the adrenal or pituitary glands.

Among the numerous functions cortisol performs in the body are metabolizing sugar and fat into energy and managing stress, WebMD explains. Cortisol levels can be affected by excessive stress, activity or injury. A typical person's cortisol levels change throughout the day, and they are usually highest in the morning and lowest during early sleep phases, so doctors strategically time cortisol tests to gauge an accurate reading of potentially high or low cortisol levels. Some medications, especially other steroids, can skew results of a cortisol test.