Cortisol (24-hour urinary free cortisol)
This test measures the amount of cortisol, a natural steroid hormone, that your body excretes in urine over a 24-hour period. It helps assess how well your adrenal glands are producing cortisol.
["Helps diagnose adrenal gland disorders, including Cushing’s syndrome or adrenal insufficiency."]
Key facts at a glance
- LOINC
- 96801-6
- Short code
- Cortis 1h p Arg SerPl-mCnc
- Synonyms
- Cortis 1h p Arg SerPl-mCnc
- Category
- hormone
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your doctor may order a 24-hour urinary free cortisol test if they suspect conditions like Cushing’s syndrome (overproduction of cortisol) or adrenal insufficiency (underproduction). It’s also used to monitor treatment effectiveness in certain cases. This test helps rule out hormonal imbalances that may cause symptoms like weight gain, fatigue, or high blood pressure.
How the Test Works
You’ll collect all your urine for a full 24-hour period, typically starting after midnight the night before the test and ending just after midnight the next day. The urine is then sent to the lab for analysis. This method provides a more accurate picture of your cortisol levels over time than a single blood or saliva sample.
What to Expect Before the Test
No special preparation is needed, but you should drink plenty of water to help flush cortisol into your urine. Avoid excessive caffeine or alcohol, as they can temporarily affect cortisol levels. If you’re on medications, let your doctor know—some may influence results.
What to Expect During the Test
You’ll collect urine in a container every time you urinate, including during sleep. Use a timer to track the 24-hour period. Store the urine in a refrigerator until you return it to the lab. Some labs may provide a collection kit with instructions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated levels may indicate Cushing’s syndrome, a condition caused by prolonged exposure to high cortisol, often due to a tumor or medication use. Low levels can signal adrenal insufficiency, where the adrenal glands aren’t producing enough cortisol, potentially due to autoimmune disease, trauma, or long-term steroid use. This test is critical for diagnosing and managing these conditions to prevent complications like bone loss or severe fatigue.
Short name
Urinary Free Cortisol
Frequently asked questions
How long does it take to get results?
Can I take my usual medications before this test?
What symptoms might indicate I need this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy