Cortisol with Triple Bolus Stimulation Test (Serum/Plasma)

Why This Test Is Done

Your doctor may recommend this test if they suspect an issue with your adrenal glands, which produce cortisol—a hormone that helps your body respond to stress, regulate metabolism, and maintain balance in fluids and electrolytes. It’s often used to check for conditions like Addison’s disease (adrenal insufficiency) or to rule out Cushing’s syndrome (overproduction of cortisol).

How the Test Works

You’ll receive three small doses of synthetic cortisol (dexamethasone) over a few hours. Blood samples are taken before and after each dose to measure your natural cortisol levels. This helps determine if your body can still produce cortisol effectively, even when exposed to extra stimulation.

What to Expect During the Test

The process is usually done in a doctor’s office or clinic. You’ll lie down comfortably while blood is drawn from a vein in your arm. The test itself takes about 4–6 hours, but you may be asked to stay for observation. Side effects from the synthetic cortisol are rare but could include mild nausea or temporary changes in blood pressure.

Preparation and Restrictions

No special preparation is needed, but inform your doctor about any medications you’re taking, especially steroids or blood pressure medications. Avoid caffeine or alcohol before the test, as they may affect cortisol levels. If you have a history of severe reactions to medications, let your doctor know beforehand.