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Cortisol, Serum (Free Cortisol)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of free cortisol, a form of the hormone cortisol, in your blood. Free cortisol is the biologically active form that helps regulate metabolism, immune response, and stress reactions.

Quick summary

Free cortisol helps your body manage stress and maintain balance in your hormones.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
58632-1
Short code
Cortis 1.5h p 1 ug/kg CRH IV Sal-sCnc
Synonyms
Cortis 1.5h p 1 ug/kg CRH IV Sal-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 Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like unexplained weight changes, fatigue, mood swings, or signs of high or low cortisol levels. It could also be part of diagnosing conditions like Cushing’s syndrome, adrenal insufficiency, or other hormonal imbalances.

What to Expect During the Test

A blood sample will be taken from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The sample is then sent to a lab for analysis.

How the Results Are Used

The results help your doctor understand whether your cortisol levels are too high or too low. They may compare your results to your typical levels or to other tests, such as a 24-hour urine cortisol test, to get a clearer picture of your health.

Common Conditions Affecting Cortisol Levels

High cortisol levels might be linked to conditions like Cushing’s syndrome (caused by excess cortisol production) or chronic stress. Low cortisol levels could indicate adrenal insufficiency, where your adrenal glands don’t produce enough cortisol.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Free Cortisol

Frequently asked questions

How often will I need this test?
The frequency depends on your symptoms and medical history. Your doctor may order this test once or repeatedly to monitor changes in your condition. Follow-up tests could be scheduled based on your treatment plan or ongoing health needs.
What do my results mean?
Your results will be compared to standard reference ranges. If your levels are outside the typical range, it may signal an underlying issue that requires further evaluation, such as additional tests or medical care. Always discuss your results with your healthcare provider.
Can lifestyle changes affect cortisol levels?
Yes, lifestyle factors like stress, diet, sleep, and exercise can influence cortisol levels. Reducing stress, maintaining a balanced diet, and getting enough sleep may help support healthy cortisol levels. Talk to your doctor about strategies tailored to your needs.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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