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Patient Test Information


  • Why Get Tested?

    To help monitor inflammatory responses such as infection, sepsis, lupus, or rheumatoid arthritis or to evaluate diabetes, stroke, and cardiovascular disease

    When To Get Tested?

    Not commonly ordered, but may be used when an individual has been diagnosed with or has signs and symptoms associated with one of the conditions listed above

    Sample Required?

    A blood sample drawn from a vein in your arm

    Test Preparation Needed?


  • What is being tested?

    Interleukin-6 (IL-6) is a protein produced by various cells. It helps regulate immune responses, which makes the IL-6 test potentially useful as a marker of immune system activation. IL-6 can be elevated with inflammation, infection, autoimmune disorders, cardiovascular diseases, and some cancers. The test measures the amount of IL-6 in the blood.

    Interleukin-6 is one of a large group of molecules called cytokines. Cytokines have multiple roles to play within the body and act especially within the immune system to help direct the body's immune response. They are a part of the "inflammatory cascade" that involves the coordinated, sequential activation of immune response pathways.

    IL-6 acts on a variety of cells and tissues. It promotes differentiation of B-cells (white blood cells that produce antibodies), promotes cell growth in some cells, and inhibits growth in others. It stimulates the production of acute phase proteins. IL-6 also plays a role in body temperature regulation, bone maintenance, and brain function. It is primarily pro-inflammatory but can also have anti-inflammatory effects.

  • How is it used?

    Interleukin-6 (IL-6) may be used to help evaluate a person who has a condition associated with inflammation, such as lupus or rheumatoid arthritis, or with infection, such as sepsis. It may also be used in the evaluation of diabetes, stroke, or cardiovascular disease.

    When is it ordered?

    The IL-6 test is not frequently ordered. C-reactive protein (CRP) is the most commonly ordered test to evaluate inflammation, but IL-6 may be ordered in conjunction with or following a CRP test when a person has signs and symptoms of an inflammatory condition or infection and a healthcare practitioner wants additional information.

    What does the test result mean?

    Normally, IL-6 is not detected in the blood or is present in low levels.

    An elevated IL-6 may mean that the person tested has an inflammatory condition. IL-6 is elevated with a variety of conditions and has been associated in some cases with an increased risk of disease development or worsening prognosis. An increase in IL-6 may be seen in conditions such as:

    • Rheumatoid arthritis, lupus, and other autoimmune disorders
    • Infections
    • Sepsis
    • Some cancers
    • Diabetes
    • Cardiovascular disease
    • Stroke

    Is there anything else I should know?

    Tocilizumab, a drug that targets the IL-6 receptor and blocks the action of IL-6, is being prescribed to some patients with rheumatoid arthritis. This drug reduces inflammation and slows the progression of joint destruction. Additional drugs that target IL-6 (or other cytokines) are being researched and developed.

    The usefulness of the IL-6 test in the medical setting is still being established. Medical researchers are actively studying IL-6 and other cytokines to better understand the normal functions of these proteins within the immune system and their association with a variety of diseases and conditions. The goal is to determine whether IL-6 is causing or contributing to disease states. This will show how it may be used to help in the diagnosis, treatment, and monitoring of diseases. It may be used to help guide treatment or even as a target for the treatment of these conditions.

    Can IL-6 be measured in samples other than blood?

    Interleukin-6 may sometimes be measured in other body fluids, such as joint fluid (synovial fluid) and cerebrospinal fluid.

    How long will it take for my results?

    This is not a routine test and not all laboratories offer this test. It is most likely that your sample will be sent to a reference laboratory for testing and it may take from one to several days for results to be available.

    Can I lower my IL-6 level?

    Concentrations of IL-6 will decrease with a decrease in inflammation but there is not currently evidence that IL-6 levels respond to lifestyle changes.

  • View Sources

    Sources Used in Current Review

    2019 review performed by Sarah E Wheeler PhD, FAACC, Assistant Professor University of Pittsburgh, Medical Director Automated Testing Laboratories UPMC Mercy, UPMC Children's Hospital, Associate Medical Director Clinical Immunopathology UPMC Presbyterian, Shadyside, Magee Women's Hospital.

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    Akbari M, Hassan-Zadeh V. IL-6 signalling pathways and the development of type 2 diabetes. Inflammopharmacology. 2018 Jun;26(3):685-698.

    Fan SL, Miller NS, Lee J, Remick DG. Diagnosing sepsis - The role of laboratory medicine. Clin Chim Acta. 2016 Sep 1;460:203-10.

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    Vainer N, Dehlendorff C, Johansen JS. Systematic literature review of IL-6 as a biomarker or treatment target in patients with gastric, bile duct, pancreatic and colorectal cancer. Oncotarget. 2018 Jul 3;9(51):29820-29841.

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    Sources Used in Previous Reviews

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    Kaptoge, S. et. al. (2014). Inflammatory Cytokines and Risk of Coronary Heart Disease New Prospective Study and Updated Meta-analysis. Medscape Multispecialty from Eur Heart J. 2014;35(9):578-589. [On-line information]. Available online at Accessed June 2014.

    Barnes, T. et. al. (2011 July). The Many Faces of Interleukin-6: The Role of IL-6 in Inflammation, Vasculopathy, and Fibrosis in Systemic Sclerosis. International Journal of Rheumatology Volume 2011, Article ID 721608 [On-line information]. Available online at Accessed June 2014.

    Scheller, J. and Rose-John, S. (2012 July 28). The interleukin 6 pathway and atherosclerosis. The Lancet, Volume 380, Issue 9839, p 338. [On-line information]. Available online at Accessed June 2014.

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