Cortisol, Serum (Free Cortisol)
This test measures the amount of free cortisol, a form of the hormone cortisol, in your blood. Cortisol helps regulate metabolism, immune response, and stress reactions.
["Free cortisol levels help assess your body’s ability to manage stress and hormone balance."]
Key facts at a glance
- LOINC
- 12560-9
- Short code
- Cortis sp5 p chal SerPl-mCnc
- Synonyms
- Cortis sp5 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 Is This Test Done?
Your doctor may order this test to evaluate conditions affecting cortisol production, such as Cushing’s syndrome (too much cortisol) or adrenal insufficiency (too little cortisol). It can also help diagnose or monitor adrenal gland disorders, stress-related issues, or hormone imbalances.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if cortisol levels are measured at specific times (e.g., morning or evening). Bring any medications or supplements you’re taking to your appointment.
How the Test Works
A blood sample is taken from a vein in your arm. The sample is sent to a lab where cortisol is measured using a sensitive immunoassay method to detect its presence in your serum.
What the Results Mean
Results are typically reported as a concentration value (e.g., micrograms per deciliter). High or low levels may indicate underlying health concerns that require further evaluation by your healthcare provider.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Cortisol plays a vital role in managing stress, immune function, and metabolism. Abnormal levels can signal conditions like adrenal disorders, hormonal imbalances, or chronic stress. Your doctor will interpret results in the context of your symptoms and medical history.
Short name
Free Cortisol
Frequently asked questions
What causes abnormal cortisol levels?
How often should I get this test?
Can diet or medications 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