Corticosteroid Serum Concentration (Mass Concentration)

Why This Test Might Be Ordered

Your doctor may order this test to diagnose or monitor conditions affecting cortisol levels, such as Cushing’s syndrome (too much cortisol), Addison’s disease (too little cortisol), or adrenal gland issues. It can also help assess stress responses, hormone imbalances, or evaluate treatments for conditions like depression or sleep disorders.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a specific cortisol testing protocol (e.g., midnight cortisol). Tell your doctor about any medications, supplements, or recent stress or illness that could affect results.

What Happens During the Test

A blood sample will be drawn from a vein in your arm by a healthcare professional. The blood is then sent to a lab for analysis. The test typically takes a few minutes, and you may feel slight discomfort, but it’s usually not painful.

What the Results Mean

Results help determine whether your cortisol levels are too high or too low, which can guide treatment decisions. Interpretation depends on timing (e.g., morning vs. evening samples) and clinical context. Your doctor will discuss these findings with you.