Cortisol (serum/plasma, mass concentration)

Why Is This Test Done?

Your doctor may order cortisol testing to check for conditions affecting your adrenal glands, such as Cushing’s syndrome (too much cortisol) or Addison’s disease (too little cortisol). It may also be used to evaluate stress responses, hormone imbalances, or to monitor treatment for adrenal-related disorders.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually causes only mild discomfort. If you’re taking medications that affect cortisol levels, let your healthcare provider know.

What Happens During the Test?

Blood is collected from a vein in your arm and sent to a lab for analysis. The test measures cortisol concentration in your serum or plasma. Results help determine if your hormone levels are within normal ranges or if further evaluation is needed.

What Do Results Mean?

Cortisol levels can vary based on time of day, stress levels, and other factors. Your doctor will interpret results in the context of your overall health and symptoms. Abnormal results may prompt additional testing or follow-up.