Cortisol is the adrenal gland-secreted hormone that plays the most significant role in the body’s stress response. Therefore, the typical blood test for adrenal fatigue consists of measuring a person’s cortisol levels four times a day. This test is sensitive to many factors including stress, eating or drinking prior to the test, low blood sugar, and pregnancy. Saliva testing of cortisol and other hormone levels, therefore, are sometimes performed in addition to the blood cortisol tests; in some cases, saliva testing is implemented in lieu of the blood test. In some cases, urine tests and imaging studies (i.e. x-rays, ultrasound computerized tomography (CT) are also used in testing for adrenal fatigue.