Cortisol, Serum, Free (24-Hour Urinary)
This test measures the amount of free cortisol (a form of the hormone cortisol) excreted in your urine over a 24-hour period. It helps assess how well your body produces cortisol, which is important for managing stress, metabolism, and other bodily functions.
["This test helps diagnose conditions like Cushing’s syndrome or adrenal insufficiency by checking cortisol levels outside the bloodstream."]
Key facts at a glance
- LOINC
- 46416-4
- Short code
- Cortis 8h p 8 mg Dex SerPl-mCnc
- Synonyms
- Cortis 8h p 8 mg Dex 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 recommend this test if they suspect an issue with your adrenal glands or pituitary gland, which control cortisol production. It’s also used to monitor conditions like Cushing’s syndrome (a hormonal disorder) or to check for overproduction of cortisol due to stress or medication.
What to Expect Before the Test
You’ll need to collect all urine for a full 24-hour period. Typically, you’ll start by emptying your bladder at home in the morning, then collect every bit of urine for the next 24 hours, including during the night. Store the urine in a refrigerator or at room temperature, and bring the entire sample to your lab on the following day.
What to Expect During the Test
No special preparation is needed beyond following the urine collection instructions. The lab will analyze the collected urine sample to measure free cortisol levels.
Possible Results and What They Mean
Results are compared to standard ranges for free cortisol in urine. High levels may indicate Cushing’s syndrome or other conditions affecting cortisol production, while low levels might suggest adrenal insufficiency or problems with cortisol metabolism.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Free cortisol in urine is a reliable way to measure cortisol activity outside the bloodstream, avoiding fluctuations caused by stress or circadian rhythms. It’s particularly useful for diagnosing conditions like Cushing’s syndrome, where cortisol levels are consistently elevated, or adrenal insufficiency, where cortisol production is insufficient.
Short name
24-Hour Free Cortisol Urine Test
Frequently asked questions
How often will I need to take this test?
What does it mean if my cortisol levels are too high?
Can I take this test at home?
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