How the Test is Performed

A 24-hour urine sample is needed. The health care provider will instruct you, if necessary, to stop taking drugs that may affect the test.

• On day 1, urinate into the toilet when you get up in the morning. Afterwards, collect all urine in a special container for the next 24 hours. Keep the container in a cool place during the test period.
• On day 2, urinate into the container when you get up in the morning.
• Cap the container. Label the container with your name, the date, the time of completion, and return it as instructed. Keep it in the refrigerator or a cool place until you return it to the laboratory.

FOR INFANTS

Thoroughly wash the area around the urethra. Open a urine collection bag (a plastic bag with adhesive paper on one end), and place it on the infant. For boys, the entire penis can be placed in the bag and the adhesive attached to the skin. For girls, the bag is placed over the labia. Diaper as usual over the secured bag.

This procedure may take a couple of attempts -- lively infants can displace the bag. Check the infant frequently and change the bag after the infant has urinated into the bag. Drain the urine into the container for transport to the laboratory.

Deliver the urine to the laboratory or your health care provider as soon as possible.

How to Prepare for the Test

No special preparation is necessary for this test. If you are taking the collection from an infant, you may need a couple of extra collection bags.

How the Test Will Feel

The test involves only normal urination, and there is no discomfort.

Why the Test is Performed

Cortisol is a steroid hormone released from the adrenal gland in response to ACTH, a hormone from the anterior pituitary gland in the brain. Cortisol levels rise and fall during the day. The highest levels occur at about 6 a.m. to 8 a.m. and the lowest levels at about midnight.

Cortisol affects many different body systems. It plays a role in:

• Bones
• Circulatory system
• Immune system
• Metabolism of fats, carbohydrates, and protein
• Nervous system
• Stress responses

The test is done to determine if you have increased or decreased cortisol production. Different diseases, such as Cushing's disease and Addison's disease, can lead to either too much or too little production of cortisol. Urine cortisol levels can help to diagnose these conditions.

Normal Results

Normal range: 10 - 100 micrograms per 24 hours (mcg/24h)

The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories.

Some labs use different measurements or may test different specimens. Normal results may sometimes be present in someone with mild Cushing syndrome. Sometimes the test may need to be repeated or another test (dexamethasone suppression test) may be done. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

Increased levels of urine cortisol may indicate:

• Severe depression
• Tumor of the adrenal gland that is producing too much cortisol
• Tumor somewhere else in the body that produces cortisol
• The pituitary gland near the brain makes too much of the hormone ACTH (called Cushing's disease), which may happen with too much growth of the pituitary gland, a tumor of the pituitary gland, or a tumor elsewhere in the body (such as the pancreas, lung, and thyroid) that produces ACTH

Decreased levels of urine cortisol may indicate:

• Addison's disease -- when the adrenal glands do not produce enough cortisol
• Hypopituitarism -- when the pituitary gland does not signal the adrenal gland to produce enough cortisol
• Congenital adrenal hyperplasia

The test may also be done in cases of exogenous Cushing syndrome.

Considerations

Factors that interfere with this test are:

• Medications, including glucocorticoids, lithium, diuretics, ketoconazole, estrogens, and tricyclic antidepressants
• Severe emotional or physical stress

Note: Due to these interfering factors, the urine cortisol may be tested on three or more separate occasions to get a more accurate picture of average cortisol production.

Alternative Names

24-hour urinary free cortisol (UFC)

References

Stewart PM, Krone NP. The adrenal cortex. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Saunders Elsevier; 2011: chap 15.

Updated: 4/11/2012

Reviewed by: Nancy J. Rennert, MD, Chief of Endocrinology & Diabetes, Norwalk Hospital, Associate Clinical Professor of Medicine, Yale University School of Medicine, New Haven, CT. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.