Serum/plasma free cortisol concentration (mass concentration)

Your healthcare provider may order this test to help check how well your body is working, look for early signs of illness, or monitor a condition you already have. The results can guide decisions about your diagnosis, treatment plan, and any follow-up care you may need.

Your healthcare provider may order this test to diagnose or monitor conditions like Cushing’s syndrome, adrenal insufficiency, or other hormonal disorders. It’s also used to check cortisol levels after certain treatments or during stress-related evaluations.

Your results are compared with a normal reference range, and values that fall above or below that range may point to a condition that needs closer attention. Keep in mind that no single number tells the whole story, so your provider will explain what your specific results mean for your overall health.

Results may be compared to your baseline or to reference ranges provided by your lab. Elevated levels could indicate overproduction of cortisol, while low levels may suggest adrenal problems. Your doctor will interpret results in the context of your symptoms and medical history.

In most cases, a small blood sample is drawn from a vein in your arm using a thin needle, although some versions of the test use a urine sample or a swab instead. The collection itself usually takes only a few minutes and is performed in a laboratory, clinic, or your provider's office.

A blood sample is drawn from a vein, usually in your arm. The sample is then processed to measure free cortisol levels using a specialized immunoassay method.

Abnormal results can come from many everyday factors, such as dehydration, recent illness, stress, certain medicines, or changes in your diet, as well as from medical conditions like infection, liver or kidney problems, or hormonal changes. Because there are many possible causes, always review your results with your provider.

High free cortisol levels might be linked to conditions like Cushing’s syndrome, steroid use, or certain tumors. Low levels could result from adrenal gland issues, pituitary disorders, or medications that affect cortisol production.