Urine cortisol is a test that measures cortisol (a stress-response hormone made by the adrenal glands) in urine, usually collected over 24 hours. Doctors commonly use it to help check for Cushing syndrome, a condition in which the body makes too much cortisol. A normal result depends on the laboratory, the test method, age, and the type of urine collection, so your report should always be read against the reference range printed by that lab. In general, a high urine cortisol result can suggest excess cortisol production, while a low result may occur with adrenal insufficiency or if the collection was incomplete.
What urine cortisol measures
Cortisol helps the body manage blood sugar, blood pressure, inflammation, and the stress response. According to the NIH and Mayo Clinic, cortisol normally rises and falls during the day, with the highest levels in the morning and lower levels later in the day. A urine cortisol test measures the amount of cortisol that the kidneys filter into urine over time, which gives a broader picture than a single blood sample.
Most often, this test measures free cortisol, meaning the portion not tightly bound to blood proteins and available to pass into urine. Doctors may order it as part of a workup for Cushing syndrome, or less commonly when they want to understand unusual symptoms that could fit either too much or too little cortisol production.
Why doctors order a urine cortisol test
Doctors usually order urine cortisol when they suspect the body is producing too much cortisol. The Cleveland Clinic, Mayo Clinic, and NHS all note that this test is one of the standard screening tests for Cushing syndrome. They may also use it to follow up on symptoms such as:
- unexplained weight gain, especially around the face, neck, or abdomen
- easy bruising
- purple stretch marks
- muscle weakness
- high blood pressure
- high blood sugar
- irregular menstrual periods
- bone loss or fractures
- mood changes such as irritability, anxiety, or depression
In some cases, a urine cortisol test may help check for adrenal problems when a doctor is considering cortisol deficiency, but other tests are usually more useful for that purpose.
How the test is done
The most common version is a 24-hour urine collection. You collect all urine passed over a full day in a special container. This matters because cortisol changes during the day, and a single sample may miss important fluctuations.
A typical collection starts after you discard the first morning urine, then save every urine sample for the next 24 hours, including the first sample of the next morning. The sample is then sent to a laboratory for measurement. Your clinician may also ask about medications, supplements, heavy alcohol use, shift work, pregnancy, or recent illness, because these factors can affect cortisol results.
If you miss a sample, the result may be less reliable. NHS guidance and laboratory manuals commonly stress that complete collection is essential for an accurate result.
Urine cortisol normal ranges
Reference ranges vary by laboratory and test method, so the number on your report is the one that matters most. Still, many adult 24-hour urine cortisol reference ranges fall roughly in the range of about 10 to 50 micrograms per 24 hours, or about 27 to 138 nanomoles per 24 hours, depending on the lab.
Some laboratories use broader cutoffs, especially for screening tests. Because of that variation, do not compare your result directly with numbers found on the internet unless you also confirm the same units, collection time, and assay method. MedlinePlus and Mayo Clinic both emphasize that results must be interpreted in context, not as a stand-alone diagnosis.
What high urine cortisol may mean
A high urine cortisol result can suggest that the body is making too much cortisol. The most important cause doctors look for is Cushing syndrome, which can happen for several reasons, including:
- a pituitary tumor that sends too much ACTH (adrenocorticotropic hormone)
- an adrenal tumor
- ectopic ACTH production, meaning another tumor makes ACTH
- long-term use of corticosteroid medicines, such as prednisone
However, a high result does not automatically mean Cushing syndrome. Stress, severe illness, depression, uncontrolled diabetes, heavy alcohol use, and some medicines can sometimes raise cortisol levels or interfere with testing. Mayo Clinic and the NIH note that doctors often repeat the test or combine it with other tests before making a diagnosis.
What low urine cortisol may mean
A low urine cortisol result can happen when the adrenal glands do not make enough cortisol, a condition called adrenal insufficiency. This may occur with primary adrenal disease, pituitary problems, or after stopping steroid medicines too quickly.
Low results can also happen if the urine collection was incomplete. That is a common reason for an unexpectedly low value, especially if some urine was missed during the 24-hour collection. For that reason, doctors often ask about the collection process before deciding what the result means.
Because urine cortisol is not the best test for every cause of cortisol deficiency, your clinician may order morning blood cortisol, ACTH, or an ACTH stimulation test if they suspect adrenal insufficiency.
Factors that can affect the result
Several things can change urine cortisol results without reflecting a true hormone disorder. According to Mayo Clinic and other endocrine references, these may include:
- corticosteroid medicines taken by mouth, inhaled, by injection, or through creams in some cases
- severe physical stress or recent surgery
- pregnancy
- obesity
- alcohol use disorder
- depression or other major illness
- shift work or major sleep disruption
- kidney problems, which can affect urine handling and interpretation
- incomplete urine collection
If your result does not fit your symptoms, your doctor may repeat the test or use a different screening test, such as late-night salivary cortisol or a low-dose dexamethasone suppression test.
How doctors interpret the result
Doctors rarely diagnose a condition from urine cortisol alone. Instead, they combine the result with your symptoms, medical history, medicines, and other hormone tests. If the urine cortisol is clearly elevated, they may repeat it and order additional testing to confirm whether cortisol production is truly abnormal.
If the result is borderline, your doctor may look for conditions that can cause “pseudo-Cushing” changes, meaning the body temporarily behaves as if cortisol is high even without a hormone-producing tumor. This can happen with severe stress, alcohol misuse, depression, or poorly controlled diabetes.
The key point is that urine cortisol is a screening tool, not a final answer. A single abnormal result usually needs follow-up.
Urine cortisol and Cushing syndrome
Cushing syndrome happens when the body is exposed to too much cortisol for a prolonged time. The NHS and Mayo Clinic state that urine free cortisol is one of the standard first-line tests used when Cushing syndrome is suspected.
If a screening test suggests excess cortisol, the next step is usually to confirm the finding with at least one other test. Doctors may then test ACTH levels and use imaging studies, such as a pituitary MRI or adrenal CT scan, to look for the source. The cause determines treatment, which may involve adjusting steroid medicines, surgery, or other specialized care.
Urine cortisol compared with other cortisol tests
Urine cortisol is only one way to evaluate cortisol status. Other common tests include:
- late-night salivary cortisol, which checks whether cortisol stays high at night
- blood cortisol, often drawn in the morning
- low-dose dexamethasone suppression test, which checks whether cortisol suppresses normally
Each test answers a slightly different question. For example, urine cortisol gives a day-long average, while saliva and blood tests can show whether cortisol follows its normal daily rhythm. Doctors often choose the test based on the symptoms, the time of day, and the condition they suspect.
How to prepare for the test
Preparation depends on your clinician’s instructions, but common advice includes:
- follow the collection instructions exactly
- tell your doctor about all medicines and supplements
- ask whether any steroid medicines should be continued or paused before testing
- avoid missing any urine during the collection period
- keep the container refrigerated if instructed
- do not change your routine unless your doctor tells you to
Do not stop prescription medicines on your own. If you use corticosteroids, even for asthma, eczema, allergies, or arthritis, let your clinician know before the test because these medicines can affect the result.
Limitations of urine cortisol
Urine cortisol is helpful, but it has limits. Results can vary from day to day, and some people with Cushing syndrome do not show a clear elevation on a single collection. That is why doctors often repeat the test or use more than one screening method.
The test also depends on accurate 24-hour collection. If the sample is incomplete, the result may underestimate the true cortisol level. In addition, some conditions can raise cortisol without a true hormone-producing disorder, so doctors interpret the number in context rather than in isolation.
When to see a doctor
See a doctor promptly if you have a urine cortisol result outside the lab’s reference range and any of the following:
- rapid or unexplained weight gain, especially in the abdomen or face
- new purple stretch marks, easy bruising, or thin skin
- muscle weakness, especially in the thighs or upper arms
- high blood pressure or high blood sugar that is hard to control
- irregular periods, new facial hair, or reduced sexual function
- frequent infections or slow wound healing
- symptoms of adrenal insufficiency such as severe fatigue, dizziness, nausea, or fainting
- a high cortisol result while taking corticosteroid medicine
- a result that seems inconsistent with how you feel, especially if the urine collection may have been incomplete
Seek urgent care if you have fainting, severe weakness, confusion, vomiting, or signs of a serious infection, especially if you might have adrenal insufficiency.
Frequently asked questions
What is the most common urine cortisol test?
The most common test is a 24-hour urine free cortisol test. It measures how much free cortisol leaves the body in urine over one full day.
What is a normal urine cortisol level?
Normal values vary by laboratory and method. Many labs use a range around 10 to 50 micrograms per 24 hours, but you should always use the reference range printed on your own lab report.
Does a high urine cortisol always mean Cushing syndrome?
No. A high result can happen with Cushing syndrome, but stress, illness, depression, alcohol use, uncontrolled diabetes, and some medicines can also affect cortisol levels. Doctors usually confirm the result with more than one test.
Can steroids affect urine cortisol?
Yes. Corticosteroid medicines can interfere with testing and may suppress or alter the body’s cortisol production. Tell your doctor about all steroid pills, inhalers, injections, creams, and nasal sprays before testing.
Why would urine cortisol be low?
A low result can suggest adrenal insufficiency, but it can also happen if the urine collection was incomplete. Your doctor may order other tests to understand the cause.
Is a urine cortisol test enough to diagnose a hormone problem?
Usually not. It is a screening tool. Doctors often combine it with blood tests, saliva tests, medication review, and sometimes imaging before making a diagnosis.
Glossary of key terms
- Adrenal glands: small glands above the kidneys that make hormones, including cortisol
- ACTH: a hormone from the pituitary gland that tells the adrenal glands to make cortisol
- Adrenal insufficiency: a condition in which the adrenal glands do not make enough cortisol
- Cushing syndrome: a condition caused by too much cortisol over time
- Cortisol: a hormone that helps regulate stress, metabolism, blood pressure, and inflammation
- Free cortisol: the portion of cortisol not tightly bound to blood proteins
- 24-hour urine collection: a test in which all urine passed over one day is collected for laboratory analysis
- Reference range: the normal range a laboratory expects for a test
Sources
- Cushing’s Syndrome – NIDDK (NIH)
- Cortisol, Free, 24 Hour, Urine – Mayo Clinic Laboratories
- Urine Free Cortisol in the Diagnosis of Cushing’s Syndrome – PMC / NIH
Further reading
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