Serum/plasma free (unbound) cortisol concentration

Why This Test Is Done

Your doctor may order this test if they suspect conditions like Cushing’s syndrome, adrenal insufficiency, or other hormonal imbalances. Free cortisol is important because it’s the active form of cortisol that your body uses, and levels can be affected by how cortisol binds to proteins in your blood.

What to Expect Before the Test

The test uses a blood sample drawn from a vein in your arm. You may feel slight discomfort, but it typically takes a few minutes to complete. No special preparation is usually needed unless your doctor specifies otherwise.

What the Results Mean

Results are not provided with specific reference ranges here. Your doctor will interpret the results in relation to your symptoms, medical history, and other tests. Elevated free cortisol may indicate conditions like Cushing’s syndrome, while low levels could suggest adrenal insufficiency or other disorders.

Common Conditions Linked to Free Cortisol Levels

High free cortisol levels may be linked to conditions such as Cushing’s syndrome (caused by excess cortisol production) or ectopic ACTH syndrome. Low levels may signal adrenal insufficiency, where the adrenal glands do not produce enough cortisol.