24-Hour Urinary Free Cortisol
This test measures the amount of cortisol, a natural steroid hormone, excreted in your urine over a 24-hour period. It helps assess how well your body produces and regulates cortisol, which plays a key role in managing stress, immune response, and metabolism.
["This test helps diagnose conditions related to cortisol imbalance, such as Cushing’s syndrome or adrenal insufficiency."]
Key facts at a glance
- LOINC
- 26529-8
- Short code
- Cortis 24h p ACTH SerPl-mCnc
- Synonyms
- Cortis 24h p ACTH SerPl-mCnc
- Category
- hormone
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 60
- 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 a 24-hour urinary cortisol test if they suspect conditions like Cushing’s syndrome (overproduction of cortisol) or adrenal gland issues (like Addison’s disease). It’s particularly useful when blood cortisol levels alone don’t provide enough information. This test also helps monitor treatment effectiveness for conditions affecting cortisol levels.
How the Test Works
You’ll collect all your urine over a full 24-hour period, typically starting after you wake up and ending just before you wake up the next morning. The urine is stored in a special container, and you’ll return it to the lab. The lab then analyzes the sample to measure cortisol levels.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to avoid certain medications or supplements that could affect cortisol levels. Follow your doctor’s instructions carefully. If you’re pregnant, breastfeeding, or have recent stress or illness, let your healthcare provider know.
What to Expect During the Test
You’ll collect urine samples at home or at a clinic, depending on your doctor’s instructions. If done at home, you’ll need to keep the urine cold (e.g., in a refrigerator) until you return it to the lab. The process is simple, but accuracy depends on following collection guidelines precisely.
Reference range
NCBI: ACTH 10-60 pg/mLN/A
Typically collected in the morning (8-10 AM). Inform your provider if taking steroid medications.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated levels may indicate Cushing’s syndrome, a condition caused by prolonged exposure to high cortisol levels, often due to a tumor or medication use. Low levels can signal adrenal insufficiency, where the adrenal glands don’t produce enough cortisol. This test helps differentiate between primary and secondary causes of cortisol imbalance, guiding treatment decisions.
Short name
24h Urine Cortisol
Frequently asked questions
How long does it take to get results?
Can I take my usual medications before this test?
What if I miss any urine collection?
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 17, 2026. · Read our editorial policy