Cortisol, Free (Serum)
This test measures the amount of free (unbound) cortisol in your blood, a hormone produced by your adrenal glands that helps regulate metabolism, immune response, and stress reactions.
["Free cortisol helps assess adrenal function and potential hormonal imbalances."]
Key facts at a glance
- LOINC
- 1443-1
- Short code
- Cortis pre 1 ug/kg CRH IV SerPl-mCnc
- Synonyms
- Cortis pre 1 ug/kg CRH IV 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
- 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 Is This Test Done?
Your doctor may order this test to evaluate adrenal gland function, diagnose conditions like Cushing’s syndrome (excess cortisol) or Addison’s disease (low cortisol), or check for cortisol-related issues during stress or certain medications.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before the blood draw if timing is critical for accurate results. Wear comfortable clothing and arrange for someone to drive you home if needed.
What Happens During the Test?
A healthcare provider will insert a small needle into a vein in your arm to draw blood. You may feel a brief pinch, but the process usually takes just a few minutes. The blood sample is then sent to a lab for analysis.
What Are Possible Results?
Results are typically reported as a concentration of cortisol in your blood. Your doctor will compare these results to your medical history and other tests to determine if further action is needed.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormally high or low free cortisol levels can indicate underlying health issues, such as hormonal disorders, adrenal tumors, or chronic stress. For example, elevated cortisol may suggest Cushing’s syndrome, while low levels could signal Addison’s disease or pituitary problems. Your doctor will interpret results in the context of your symptoms and other tests.
Short name
Free Cortisol
Frequently asked questions
How often should I get this test?
What can affect my cortisol levels?
Do I need to do anything special after the blood draw?
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