Cortisol, Free, 24-Hour Urinary

Why This Test Matters

Cortisol is a hormone produced by your adrenal glands that helps regulate stress responses, metabolism, and immune function. Free cortisol in urine reflects your body’s natural cortisol levels without interference from proteins or other substances. This test is particularly useful for detecting chronic cortisol excess or deficiency that may not be detected by blood tests alone.

When It’s Ordered

Your doctor may recommend this test if they suspect conditions like Cushing’s syndrome (excess cortisol), adrenal insufficiency (low cortisol), or other hormonal imbalances. It’s often used in patients with unexplained weight gain, fatigue, high blood pressure, or symptoms of prolonged stress.

What to Expect Before the Test

No special preparation is needed for this test. You’ll collect your urine for 24 hours, starting right after you wake up and ending just before you wake up the next morning. Store the urine in a refrigerator or freezer until you bring it to the lab.

What to Expect During the Test

You’ll provide a full 24-hour urine sample, which includes all urine produced during that time. The lab will analyze the sample for free cortisol levels. This test is typically painless and does not require any special equipment at home.