Cortisol, Serum, Free (Mass Concentration)
This test measures the amount of free cortisol, a hormone produced by your adrenal glands, in your blood. Free cortisol is the active form that circulates in your bloodstream and is important for managing stress, metabolism, and other bodily functions.
["Free cortisol helps assess adrenal gland function and potential hormonal imbalances."]
Key facts at a glance
- LOINC
- 59273-3
- Short code
- Cortis p 6 mg Dex SerPl-mCnc
- Synonyms
- Cortis p 6 mg Dex 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 healthcare provider may order a free cortisol test to diagnose or monitor conditions such as Cushing’s syndrome (overactive adrenal glands), adrenal insufficiency (underactive adrenal glands), or other hormonal disorders. It can also help evaluate stress responses or rule out certain endocrine issues.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if instructed by your provider. Avoid caffeine or stress-inducing activities for a few hours beforehand to help ensure accurate results.
What Happens During the Test?
A healthcare professional will draw blood from a vein in your arm. The sample is then sent to a lab for analysis. The process takes about 15 minutes, and you may feel slight discomfort or bruising at the injection site.
What Are Possible Results?
Results are compared to reference ranges provided by your lab, but exact values can vary by lab. High cortisol levels may suggest conditions like Cushing’s syndrome, while low levels could indicate adrenal insufficiency or other disorders.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Free Serum Cortisol
Frequently asked questions
Cortisol plays a key role in regulating metabolism, immune response, and stress reactions. Abnormal levels can indicate hormonal imbalances, adrenal disorders, or other systemic conditions. Your provider will interpret results in the context of your symptoms and medical history.
Results are typically available within 1–3 business days, depending on your lab and testing schedule. Follow-up with your healthcare provider to discuss findings and next steps.
High cortisol may lead to symptoms like weight gain, fatigue, or high blood pressure, while low cortisol can cause dizziness, weakness, or frequent infections. Your provider will guide you on whether further testing or treatment is needed.
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