Cortisol (Free, Urine 24-Hour)
This test measures the amount of free cortisol excreted in your urine over a 24-hour period. Free cortisol is the active form of cortisol that circulates in your blood and is eliminated through urine.
["Assesses cortisol levels over a full day to help diagnose conditions like adrenal insufficiency or Cushing’s syndrome."]
Key facts at a glance
- LOINC
- 24394-9
- Short code
- Cortis 17h p 1 mg Dex SerPl-sCnc
- Synonyms
- Cortis 17h p 1 mg Dex SerPl-sCnc
- 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 this test if they suspect hormonal imbalances affecting your adrenal glands. Common reasons include unexplained fatigue, weight changes, or symptoms like high blood pressure, muscle weakness, or unusual hair growth. It can also be used to monitor conditions like Cushing’s syndrome or adrenal insufficiency.
What to Expect Before the Test
You’ll collect all your urine for a full 24-hour period, starting right after you wake up and ending just before you wake up the next morning. Store the urine in a clean container at room temperature. Do not add preservatives unless instructed. Follow any specific instructions your lab provides to ensure accuracy.
What to Expect During the Test
No special preparation is needed beyond collecting your urine sample. The test involves measuring the cortisol content in your urine, which is then analyzed in a lab.
What the Results Mean
Results help determine if your cortisol levels are too high or too low over time. Elevated levels may indicate conditions like Cushing’s syndrome, while low levels could suggest adrenal gland issues or other hormonal problems. Your doctor will interpret the results in the context of your symptoms and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Cortisol is a steroid hormone produced by the adrenal glands that plays a key role in managing stress, immune response, and metabolism. Abnormal levels can lead to serious health issues, such as difficulty managing stress, weight changes, muscle weakness, or even life-threatening conditions like adrenal crisis. This test is particularly useful for diagnosing conditions where cortisol production is consistently elevated or deficient over a full day, rather than just at specific times.
Short name
Urine Free Cortisol (24-Hour)
Frequently asked questions
How is this test different from a blood cortisol test?
What if I miss any urine during the 24-hour collection?
Can I take medications or supplements that might affect 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