Cortisol, Free (Serum or Plasma)
This test measures the amount of free cortisol, a form of the hormone cortisol that circulates freely in your blood. Free cortisol is important for regulating metabolism, immune response, and stress reactions.
["Free cortisol helps your body manage stress and maintain balance in your hormones."]
Key facts at a glance
- LOINC
- 93484-4
- Short code
- Cortis 5M pre 1 ug/kg CRH IV SerPl-mCnc
- Synonyms
- Cortis 5M 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
What Is Free Cortisol Used For?
Free cortisol is primarily used to diagnose conditions related to the adrenal glands, such as Cushing’s syndrome (overproduction of cortisol) or Addison’s disease (underproduction of cortisol). It can also help assess adrenal function in patients with suspected hormonal imbalances or stress-related issues.
Why Is Free Cortisol Tested?
Your doctor may order this test if you have symptoms like unexplained weight changes, fatigue, high blood pressure, or signs of hormonal disorders. It’s also used in research or specialized evaluations for adrenal function.
How Is the Test Performed?
A blood sample is drawn from a vein in your arm. The sample is collected in either a serum or plasma tube, depending on the lab’s protocol. Free cortisol is measured after separating the blood components from cells.
What Does the Test Result Mean?
Results are not provided with specific reference ranges in this generic format, as they depend on the lab’s methods and clinical context. Your doctor will interpret the results in relation to your symptoms and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Free cortisol levels can indicate adrenal gland disorders, stress responses, or other hormonal imbalances. Abnormal results may prompt further testing, such as cortisol levels at different times of day or additional hormone evaluations.
Short name
Free Cortisol
Frequently asked questions
Why might my doctor request this test?
How soon will I get my results?
Can I eat or drink anything before this test?
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