Cortisol, Serum, Free (24-Hour Urinary Excretion)
This test measures the amount of free cortisol your body excretes in urine over 24 hours, helping assess adrenal function and potential hormone imbalances.
["This test helps diagnose conditions like Cushing’s syndrome or adrenal insufficiency by tracking cortisol levels outside the bloodstream."]
Key facts at a glance
- LOINC
- 58691-7
- Short code
- Cortis sp12 p chal SerPl-sCnc
- Synonyms
- Cortis sp12 p chal 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 Matters
Cortisol is a hormone produced by your adrenal glands that helps regulate stress responses, metabolism, and immune function. Free cortisol in urine reflects how much your body naturally releases over a full day, providing a more comprehensive picture than blood tests alone. This test is particularly useful for detecting chronic cortisol overproduction (Cushing’s syndrome) or underproduction (adrenal insufficiency) that may not show up clearly in blood tests.
When It’s Ordered
Your doctor may recommend this test if you have symptoms like unexplained weight changes, fatigue, high blood pressure, or signs of hormonal imbalances. It’s also used in research or specialized evaluations for conditions like pituitary disorders or adrenal tumors.
How the Test Works
A urine sample is collected over 24 hours (typically from one morning to the next morning). The sample is then analyzed to measure free cortisol levels, which are compared to a reference range for your age and sex. This method avoids interference from cortisol bound to proteins in the bloodstream.
What to Expect
You’ll need to collect all urine for a full 24-hour period, discarding the first morning sample and saving the last one. Store the sample in a refrigerator or freezer to maintain accuracy. Follow your healthcare provider’s instructions carefully to ensure valid results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated cortisol levels in urine may indicate Cushing’s syndrome (excess cortisol from tumors or prolonged steroid use), while low levels could signal adrenal insufficiency (e.g., from autoimmune disease or trauma). This test helps distinguish between different causes of hormonal imbalances and guides treatment decisions, such as medication adjustments or further diagnostic testing.
Frequently asked questions
What does a high cortisol level mean?
What does a low cortisol level mean?
How often should I get 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