Cortisol, Free (Serum)
This test measures the amount of free cortisol, a form of the hormone cortisol that circulates freely in your bloodstream. Free cortisol is important for regulating stress responses, metabolism, and other bodily functions.
Your doctor may order this test to check for conditions affecting cortisol levels, like Cushing’s syndrome or adrenal insufficiency.
Key facts at a glance
- LOINC
- 47606-9
- Short code
- Cortis 1h p 1 ug/kg CRH IV SerPl-sCnc
- Synonyms
- Cortis 1h p 1 ug/kg CRH IV 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
- 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 Is Done
Your healthcare provider may recommend a free cortisol test if you have symptoms linked to hormonal imbalances, such as unexplained weight changes, fatigue, high blood pressure, or unusual mood swings. It could also be part of an evaluation for conditions like Cushing’s syndrome (too much cortisol) or Addison’s disease (too little cortisol).
What to Expect Before the Test
No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm, similar to other blood tests. If you’re taking medications that affect cortisol levels (like steroids), let your doctor know before the test.
What the Results Mean
Free cortisol levels can vary based on your body’s natural rhythms and other health factors. Your doctor will compare your results to standard reference ranges and consider your overall health and symptoms to interpret them. High or low levels may indicate underlying medical issues that need further evaluation.
Common Conditions Linked to Free Cortisol
Abnormally high free cortisol levels may suggest conditions like Cushing’s syndrome, which can cause weight gain, muscle weakness, or high blood pressure. Low levels might point to adrenal insufficiency, leading to fatigue, dizziness, or low blood pressure. Your doctor will work with you to determine the best next steps based on your test results and symptoms.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Free Cortisol
Frequently asked questions
Will my free cortisol test results affect my medications?
Can I still take my usual medications on the day of the test?
How long will I need to wait for my 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