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Interleukin-6 (IL-6) concentration in serum/plasma

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

This test measures the amount of interleukin-6, a protein involved in inflammation and immune response, in your blood.

Quick summary

["IL-6 helps your body respond to infections, injuries, and chronic conditions by signaling inflammation."]

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

Key facts at a glance

LOINC
44603-9
Short code
M-IgM CSF Ql IFE
Synonyms
M-IgM CSF Ql IFE
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
immunofixation
CPT
82784
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

What Is Interleukin-6 Used For?

IL-6 is measured to assess inflammation, monitor autoimmune diseases, evaluate responses to treatments, or investigate symptoms like fever, fatigue, or swelling that may stem from an overactive immune system or infection.

Common Uses in Medical Care

Doctors may order IL-6 testing when diagnosing or managing conditions such as rheumatoid arthritis, lupus, or other inflammatory disorders. It can also help track how well certain treatments are working or identify hidden inflammation in conditions like cancer or heart disease.

When Might You Need This Test?

You might have this test if you have symptoms like persistent fever, unexplained weight loss, joint pain, or fatigue, especially if other tests don’t explain your condition. It’s also used in research or specialized care for rare inflammatory diseases.

What to Expect Before the Test

No special preparation is usually needed, but your doctor may ask you to fast for a few hours before the blood draw. A small needle will be used to collect a blood sample from a vein, typically in your arm.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IL-6

Frequently asked questions

Why might my IL-6 levels be checked repeatedly?
Your doctor may monitor IL-6 levels over time to see how your body responds to treatments for inflammation or autoimmune diseases. High levels can indicate active inflammation, while low levels may suggest the condition is under control or improving.
What do extremely high or low IL-6 levels mean?
Extremely high IL-6 levels often signal severe inflammation, infection, or a flare-up of an autoimmune disease. Very low levels may mean your body isn’t producing enough of this protein, which could affect immune function or response to treatments.
Can diet or lifestyle affect IL-6 levels?
Yes, diet, exercise, and stress can influence inflammation. Reducing processed foods, managing weight, and practicing stress-reduction techniques may help lower IL-6 levels, but results vary by individual.
  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