A cortisol urine test measures the amount of the steroid hormone cortisol in the urine.
24-hour urinary free cortisol (UFC)
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.
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.
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.
The test involves only normal urination, and there is no discomfort.
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:
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 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.
Increased levels of urine cortisol may indicate:
Decreased levels of urine cortisol may indicate:
The test may also be done in cases of exogenous Cushing syndrome.
Factors that interfere with this test are:
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.
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.