Skip to content

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 that circulates freely in your blood. Cortisol helps regulate metabolism, immune response, and stress reactions.

Quick summary

["Free cortisol helps assess adrenal function and potential stress-related hormone imbalances."]

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

Key facts at a glance

LOINC
25618-0
Short code
Cortis sp1 p chal SerPl-sCnc
Synonyms
Cortis sp1 p chal 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
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, or mood swings that could be linked to hormonal imbalances. It may also be used to diagnose conditions such as Cushing’s syndrome or Addison’s disease, or to monitor treatment for these conditions.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your arm to draw blood. The process usually takes a few minutes. If you’re taking medications that affect cortisol levels, let your provider know.

What the Results Mean

Results help determine if your cortisol levels are too high or too low. Abnormal levels may indicate issues with your adrenal glands or pituitary gland, which control hormone production. Your provider will interpret the results in relation to your symptoms and medical history.

Common Conditions This Test Helps Diagnose

This test can help diagnose conditions like Cushing’s syndrome (too much cortisol), Addison’s disease (too little cortisol), or evaluate stress responses. It may also be used in research or specialized clinical settings to assess adrenal function.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Cortisol’s Role in Health

Short name

Free Cortisol

Frequently asked questions

How often will I need this test?
The frequency depends on your medical condition and treatment plan. Some patients need this test monthly, others yearly, or even less often. Your healthcare provider will schedule follow-up tests as needed to monitor your condition.
What are the normal ranges for cortisol?
There isn’t a single standard range because cortisol levels fluctuate throughout the day. Your provider will use your specific results and medical context to determine if levels are within a healthy range for you.
Can diet or stress affect cortisol levels?
Yes, both diet and stress can influence cortisol levels. High-stress situations or certain foods may temporarily raise cortisol. If you suspect stress is affecting your results, discuss lifestyle changes with your provider.
  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