What is a cortisol urine test?
A cortisol urine test is also called a urinary-free cortisol test or UFC test. It measures the amount of cortisol in your urine.
Cortisol is a hormone produced by the adrenal glands, which are located on top of the kidneys. Cortisol is often released in response to physical or emotional stress.
Cortisol functions by:
- controlling blood sugar
- regulating blood pressure
- fighting infections
- playing a role in mood regulation
- playing a role in the metabolism of carbohydrates, fats, and proteins
Cortisol levels naturally rise and fall throughout the day. They’re usually highest in the morning and lowest around midnight, but there are also variations that depend on the person.
When this 24-hour cycle is disrupted, however, the body can produce too much or too little cortisol. A cortisol test can be performed to determine the underlying cause of abnormal cortisol levels.
There are different types of cortisol tests that may be performed, including blood, saliva, and urine tests. The urine test is done over a period of 24 hours.
The cortisol urine test tends to be more comprehensive than the other types of cortisol tests. It measures the total amount of cortisol excreted into the urine over a 24-hour period.
Blood tests or saliva tests, however, only measure cortisol levels at a particular time of day. Some people also find blood tests to be stressful, and since the body releases more cortisol during times of stress, the results may not be as precise.
In some cases, your doctor may order both a cortisol urine test and another type of cortisol test to obtain more accurate results.
Why is a cortisol urine test performed?
Your doctor may order a cortisol urine test if you’re showing symptoms of a medical condition that causes cortisol levels to rise or fall.
Symptoms of high cortisol levels
Cushing syndrome is a collection of symptoms associated with high cortisol levels. The most common symptoms include:
- increased urination
- increased thirst
- fatty tissue deposits, especially in the midsection and upper back
- pink or purple stretch marks on the skin
- weight gain
- muscle weakness
- thinning skin that bruises easily
Women may have irregular periods and excess facial and chest hair. Children may show delayed physical or cognitive development.
Symptoms of low cortisol levels
The symptoms of low cortisol levels often emerge slowly. At first, they may only appear during times of extreme stress, but they’ll gradually increase in intensity over several months.
Potential symptoms include:
- weight loss
- muscle weakness
- abdominal pain
When cortisol levels abruptly drop to life-threatening levels, an acute adrenal crisis may occur.
The symptoms of an acute adrenal crisis include:
- darkening of the skin
- extreme weakness
- a fever
- loss of appetite
- a sudden onset of severe pain in the lower back, abdomen, or legs
Call 911 or your local emergency number if you’re having these symptoms. An acute adrenal crisis is a serious medical emergency that requires immediate treatment.
How do I prepare for a cortisol urine test?
It’s important to tell your doctor about any prescription drugs or over-the-counter medicines you’re taking. Certain medications can interfere with the accuracy of the cortisol urine test. These include:
- tricyclic antidepressants
Your doctor may instruct you to stop taking medications that could affect the results. However, you should never stop taking your medications unless your doctor tells you to do so.