Cortisol, Serum or Plasma, Free (24-Hour Urine Collection)
This test measures the amount of free cortisol excreted in your urine over a 24-hour period. Free cortisol is the active form of the hormone cortisol, which helps regulate stress responses, metabolism, and other bodily functions.
["Assesses long-term cortisol levels to diagnose conditions like Cushing’s syndrome or adrenal insufficiency."]
Key facts at a glance
- LOINC
- 12558-3
- Short code
- Cortis sp3 p chal SerPl-mCnc
- Synonyms
- Cortis sp3 p chal 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 you have an overactive or underactive adrenal gland, unusual weight changes, or symptoms linked to hormonal imbalances. It’s also used to monitor treatment for conditions like Cushing’s syndrome or adrenal tumors.
What to Expect Before the Test
You’ll need to collect all urine for 24 hours, starting and ending with a sample at the same time each day. Store samples in a refrigerator until you return them to the lab. Follow your doctor’s instructions carefully to ensure accurate results.
What Happens During the Test
No special preparation is needed beyond the 24-hour urine collection. The lab will analyze the urine sample for free cortisol levels.
Possible Results and Next Steps
Results may be compared to reference ranges provided by your healthcare provider. Elevated levels could indicate conditions like Cushing’s syndrome, while low levels may suggest adrenal insufficiency or other hormonal disorders. Your doctor will discuss the results and next steps with you.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Cortisol plays a key role in managing stress, immune response, and metabolism. Abnormal levels can signal underlying health issues, such as hormonal imbalances, adrenal gland disorders, or certain cancers. This test helps diagnose and monitor these conditions by tracking cortisol excretion over time.
Short name
Free Cortisol (Urine)
Frequently asked questions
What does a high or low cortisol level mean?
How long does it take to get my results?
Can I take medications before 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