What Is a Cortisol Test?

Medical practitioners use a variety of medical tests as a first step toward diagnosing disease and other underlying conditions. At some point, your doctor might prescribe a cortisol test. But what is a cortisol test? What is cortisol? Read on for the answers, as well as additional facts about cortisol.

What is cortisol?

Cortisol is a stress hormone that primes the body to take action. Cortisol is produced by the adrenal glands, which lay on top of the kidneys. Blood levels of cortisol normally fluctuate, peaking in the morning, signaling the cessation of the sleep cycle, and waning in the evening, promoting restful and healthy sleep. But cortisol can rise at any time in response to perceived stress, whether internal (e.g. worrying over something that happened during the day) or external (e.g. being chased by a bear).

What is a cortisol test?

A cortisol test is a blood test designed to measure the body's current level of cortisol production. Elevated or lowered levels of cortisol can signal the presence of an underlying condition. Detecting cortisol abnormalities can be the first step in a comprehensive battery of tests needed to identify the cause of the problem.

How is a cortisol test administered?

A cortisol test can be administered through sampling the blood, urine or saliva. The type of test is chosen depending on physician preference and the kind of problem suspected. For example, saliva tests are used to identify possible stress-related problems, whereas blood tests are used to help diagnose underlying disease. If an abnormal concentration of cortisol is detected, the physician will order either a dexamethasone suppression test (in response to excess production of cortisol) or an ACTH stimulation test (in response to insufficient production of cortisol).

Possible underlying conditions

Abnormalities in cortisol production could signal a number of conditions. When cortisol levels are higher than expected, a possible diagnosis could be adrenal or ectopic tumors, also called Cushing's syndrome. When levels of cortisol are excessively low, it might signal a low-functioning pituitary gland, also called Addison's disease. A cortisol test also might be required for other conditions, such as when a patient is suffering from acute adrenal crisis.

Considerations

Cortisol can be affected by conditions and circumstances other than the aforementioned diseases. Excess emotional stress, physical stress, pregnancy, certain medications and thyroid conditions also can wreak havoc on normal cortisol patterns. Additionally, working irregular shifts can, in time, cause natural cortisol rhythms to fluctuate. Cortisol testing is a useful diagnostic tool, often serving as the first step in helping a physician determine whether an underlying problem exists.