Serum/Plasma Free Cortisol by Electrochemiluminescence Immunoassay (High Sensitivity)
This test measures the amount of free (unbound) cortisol in your blood, which is the active form of the hormone cortisol. Cortisol is involved in regulating metabolism, immune response, and stress reactions.
["Assessing your cortisol levels can help diagnose conditions like Cushing’s syndrome or adrenal insufficiency."]
Key facts at a glance
- LOINC
- 56560-6
- Short code
- GH 4.5h p chal SerPl-mCnc
- Synonyms
- GH 4.5h p chal SerPl-mCnc
- Category
- chemistry
- 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 This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms or signs of hormonal imbalances, such as unexplained weight changes, fatigue, high blood pressure, or unusual mood swings. It could also be used to monitor conditions like adrenal gland disorders or to check for cortisol-related issues before or after certain treatments.
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 blood draw if cortisol levels are being checked at specific times of the day. If you’re taking medications that affect cortisol, inform your provider beforehand.
What the Test Results Mean
Free cortisol levels can vary based on your body’s natural rhythms and stress levels. Results are interpreted by your healthcare provider in relation to your overall health and symptoms. Abnormal results may indicate conditions requiring further evaluation or treatment.
Common Conditions Linked to Cortisol Testing
High cortisol levels might suggest conditions like Cushing’s syndrome (overactive adrenal glands), while low levels could indicate adrenal insufficiency (Addison’s disease) or other hormonal disorders. This test helps differentiate between these possibilities.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
High-Sensitivity Free Cortisol
Frequently asked questions
Will this test show if I have diabetes?
Can I take my usual medications before the blood draw?
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