Cortisol, Serum (Free)
This test measures the amount of free cortisol, a form of the hormone cortisol, in your blood. Free cortisol is the active form that travels freely in your bloodstream and is not bound to proteins.
["Free cortisol helps regulate your body’s response to stress and supports normal metabolism and immune function."]
Key facts at a glance
- LOINC
- 25627-1
- Short code
- Cortis sp8 p chal SerPl-sCnc
- Synonyms
- Cortis sp8 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 Might Be Ordered
Your doctor may recommend this test if they suspect conditions like Cushing’s syndrome (overactive cortisol production), adrenal insufficiency (underactive adrenal glands), or other hormonal imbalances. It can also help diagnose issues with the pituitary gland or adrenal glands that affect cortisol levels.
What to Expect Before the Test
No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually takes a few minutes. If you’re taking medications that affect cortisol levels (like steroids), let your doctor know beforehand.
What the Results Mean
Results are interpreted by your doctor based on your symptoms, medical history, and other tests. Abnormally high or low cortisol levels may indicate underlying health concerns that need further evaluation.
Common Conditions Linked to Cortisol Levels
High cortisol levels might be linked to conditions such as Cushing’s syndrome, chronic stress, or certain medications. Low cortisol levels could signal adrenal insufficiency or other hormonal disorders.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Cortisol plays a vital role in managing stress responses, immune function, and metabolism. Abnormal levels can signal serious health issues, including hormonal imbalances, adrenal gland disorders, or other systemic conditions that require medical attention.
Short name
Free Cortisol
Frequently asked questions
What triggers cortisol testing?
How is cortisol measured in this test?
Can diet or stress affect cortisol test results?
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