Cortisol (Serum) – 24-Hour Urinary Free Cortisol
This test measures the amount of cortisol, a natural steroid hormone, excreted in your urine over a full day. It helps assess how well your body produces and balances cortisol, which plays a key role in stress response and metabolism.
["This test helps diagnose conditions related to abnormal cortisol levels, such as Cushing’s syndrome or adrenal insufficiency."]
Key facts at a glance
- LOINC
- 1428-2
- Short code
- Cortis 50H p 500 ug Dex SerPl-mCnc
- Synonyms
- Cortis 50H p 500 ug 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 order this test if they suspect conditions like Cushing’s syndrome (too much cortisol) or adrenal gland issues (too little cortisol). It can also be used to monitor treatment for hormone-related disorders. Unlike a single blood cortisol test, this 24-hour urine test provides a more complete picture of your cortisol levels throughout the day.
How the Test Works
You’ll collect your urine for a full 24-hour period, typically starting and ending at the same time each day. The urine is then sent to a lab for analysis to measure cortisol levels. This method helps identify patterns of cortisol excretion that may not be detected by a single blood sample.
Sample Collection Process
Follow your healthcare provider’s instructions carefully. You’ll need to collect all urine produced in a 24-hour period, including the first urine of the next day if the collection starts at midnight. Store the urine samples properly to maintain accuracy.
What to Expect Before the Test
No special preparation is usually needed, but avoid taking certain medications that may affect cortisol levels (like some steroids) without consulting your doctor. Staying hydrated and maintaining normal activity levels can help ensure accurate results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated cortisol levels in urine may indicate Cushing’s syndrome, excessive stress, or other conditions affecting cortisol production. Low levels could suggest adrenal insufficiency, pituitary disorders, or medications that suppress cortisol. This test helps diagnose and monitor these conditions and guide treatment decisions.
Short name
24-Hour Urine Cortisol
Frequently asked questions
What does a high cortisol level in urine mean?
What does a low cortisol level in urine mean?
Can diet or medications 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