Cortisol (24-hour urinary free cortisol)

Your doctor ordered this test to learn more about how your body is working and to look for signs of a condition that may need care. The results give your care team important information that cannot be found during a regular physical exam, and they help guide decisions about your diagnosis and treatment plan.

Your doctor may order a 24-hour urinary cortisol test if they suspect conditions that affect your adrenal glands, such as Cushing’s syndrome (too much cortisol) or adrenal insufficiency (too little cortisol). It can also be used to monitor treatment responses or rule out other hormonal imbalances. This test is particularly useful because cortisol levels fluctuate throughout the day, and measuring urine over 24 hours provides a more accurate overall picture.

During this test, a small sample or measurement is collected so it can be examined in a laboratory or with specialized equipment. The process is designed to be safe and straightforward, and the information gathered helps your healthcare provider understand what is happening inside your body.

You’ll collect your urine in a special container for all 24 hours, starting after you wake up and ending just before you wake up the next morning. The test measures cortisol that naturally appears in your urine. This method helps avoid the variability that can occur with blood or saliva tests alone.

Before your test, follow any specific instructions from your healthcare team, because good preparation helps make sure your results are accurate. You may be asked to avoid certain foods, drinks, or medicines for a period of time, so write down any questions you have and ask them before the day of your appointment.

No special preparation is needed, but you should avoid certain medications or supplements that might affect cortisol levels, such as some steroids or blood pressure medications. Follow your doctor’s instructions carefully for accurate results.

When you arrive, a trained member of your care team will explain each step and answer your questions before the test begins. The test is usually quick, and most people find it only mildly uncomfortable at most. You can ask the staff to pause at any time, and once it is finished you can usually go home the same day.

You’ll need to keep a record of all urine output in the container, including any leaks or spills. Some labs may provide a prepaid mail-back container for convenience. If you miss any urine, the test may need to be repeated.