Cortisol, Serum (Free Cortisol)
This test measures the amount of free cortisol, a hormone produced by your adrenal glands. Free cortisol is the active form of cortisol that circulates in your blood and is important for regulating stress responses, metabolism, and immune function.
Free cortisol helps your body manage stress and maintain balance in your body’s systems.
Key facts at a glance
- LOINC
- 58671-9
- Short code
- Cortis 45M p 1 ug/kg CRH IV Sal-sCnc
- Synonyms
- Cortis 45M p 1 ug/kg CRH IV Sal-sCnc
- Category
- hormone
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 86701
- 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 Might Be Ordered
Your healthcare provider may order a free cortisol test to diagnose or monitor conditions such as Cushing’s syndrome (overactive adrenal glands), adrenal insufficiency (underactive adrenal glands), or to check for cortisol-related issues like adrenal tumors or pituitary disorders. It can also be used to evaluate stress responses or hormone imbalances.
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, such as some steroids or blood pressure medications. If you’re taking these, let your provider know.
What Happens During the Test
A blood sample will be drawn from a vein in your arm. This is a quick and typically painless process. The sample is sent to a lab for analysis.
What the Results Mean
Results are interpreted based on your symptoms, medical history, and other tests. Abnormal levels may indicate hormonal imbalances or conditions affecting your adrenal glands or pituitary gland.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Free cortisol levels can provide critical clues about adrenal gland function. High cortisol levels may suggest Cushing’s syndrome or excessive stress responses, while low levels could indicate adrenal insufficiency or problems with the pituitary gland. This test helps guide treatment decisions for managing hormone-related disorders.
Short name
Free Cortisol
Frequently asked questions
What causes abnormal cortisol levels?
How long does it take to get results?
Can lifestyle changes affect cortisol levels?
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