A 24-hour urine sample is needed. You will need to collect your urine over 24 hours. Your health care provider will tell you how to do this. Follow instructions exactly so that the results are accurate.
Because cortisol level rises and falls throughout the day, the test may need to be done three or more separate times to get a more accurate picture of average cortisol production.
How to Prepare for the Test
You may also be asked not to do any vigorous exercising the day before the test.
You may also be told to temporarily stop taking medicines that can affect the test, including:
Human-made (synthetic) glucocorticoids, such as hydrocortisone, prednisone and prednisolone
How the Test will Feel
The test involves only normal urination. There is no discomfort.
Why the Test is Performed
The test is done to check for increased or decreased cortisol production. Cortisol is a glucocorticoid (steroid) hormone released from the adrenal gland in response to adrenocorticotropic hormone (ACTH). This is a hormone released from the pituitary gland in the brain. Cortisol affects many different body systems. It plays a role in:
Blood pressure control
Immune system function
Metabolism of fats, carbohydrates, and protein
Nervous system function
Different diseases, such as Cushing syndrome and Addison disease, can lead to either too much or too little production of cortisol. Measuring urine cortisol level can help diagnose these conditions.
Normal range is 10 to 100 micrograms per 24 hours (mcg/24h).
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
A higher than normal level may indicate:
Cushing disease, in which the pituitary gland makes too much ACTH because of excess growth of the pituitary gland or a tumor in the pituitary gland
Addison disease in which the adrenal glands do not produce enough cortisol
Hypopituitarism in which the pituitary gland does not signal the adrenal gland to produce enough cortisol
Suppression of normal pituitary or adrenal function by glucocorticoid medications including pills, skin creams, eyedrops, inhalers, joint injections, chemotherapy
There are no risks with this test.
Guber HA, Farag AF. Evaluation of endocrine function. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 24.
Stewart PM, Krone NP. The adrenal cortex. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 15.
Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.