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Interleukin-6 (IL-6)

Published: July 27, 2026Updated: August 25, 2026

IL-6 is a cytokine that plays a crucial role in inflammation and immune response. It is measured to assess the level of inflammation in the body.

Quick summary

IL-6 is a key inflammatory biomarker used to evaluate immune system activation and inflammation.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
pg/mL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche IL-6, Abbott IL-6
interpretation: {"text":"IL-6 levels below 0–5 pg/mL are generally considered normal and indicate a low level of inflammation.","label":"Low Levels"}; {"text":"Levels above 5 pg/mL may suggest an inflammatory condition, infection, or other underlying health issues.","label":"High Levels"}

Interleukin-6 (IL-6) is a cytokine, a type of protein that acts as a signaling molecule in the immune system. It is involved in the acute phase response, which is a rapid inflammatory response to infection, injury, or trauma.

Elevated levels of IL-6 are associated with various inflammatory conditions, including rheumatoid arthritis, systemic juvenile idiopathic arthritis, and certain types of cancer. It is also used to monitor the effectiveness of anti-inflammatory treatments.

The normal reference range for IL-6 is typically between 0–5 pg/mL. Levels above this range may indicate an ongoing inflammatory process or infection.

Frequently asked questions

What conditions can cause elevated IL-6 levels?
Elevated IL-6 levels can be caused by inflammatory conditions such as rheumatoid arthritis, systemic juvenile idiopathic arthritis, and certain cancers.
How is IL-6 testing used in clinical practice?
IL-6 testing is used to assess the level of inflammation in the body, monitor disease activity, and evaluate the effectiveness of anti-inflammatory treatments.
  1. 1
    Interleukin-6Source
  2. 2
    IL-6 as a biomarker of inflammation in rheumatic diseasesSource

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 25, 2026. · Read our editorial policy