Interleukin-6

Also Known As

IL-6

Formal Name

Interleukin-6

This article was last reviewed on

September 15, 2014.

This article waslast modified on November 5, 2017.

At a Glance

Why Get Tested?

To help evaluate conditions such as diabetes and cardiovascular disease or conditions associated with inflammation such as lupus and rheumatoid arthritis or with infection, such as sepsis

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?

None

You may be able to find your test results on your laboratory's website or patient portal. However, you are currently at Lab Tests Online. You may have been directed here by your lab's website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab's website or portal, or contact your healthcare practitioner in order to obtain your test results.

Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

What is being tested?

Interleukin-6 (IL-6) is a protein produced by immune 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 leukemias. The test measures the amount of IL-6 in the blood.

Interleukin-6 is a 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 is produced by white blood cells (leukocytes) and 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 the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

Common Questions

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 or cardiovascular disease.

IL-6 is a cytokine, a protein produced by immune cells that acts on other cells to help regulate and/or promote an immune response. It also stimulates the production of acute phase reactants, proteins that increase in the blood with conditions that cause inflammation or tissue injury.
When is it ordered?

The IL-6 test is not frequently ordered. C-reactive protein (CRP) is the most commonly ordered test to evaluate for 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 health practitioner wants additional information.
What does the test result mean?
Normally, IL-6 is not detected in the blood or is present in low quantities.

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 leukemias

Diabetes

Cardiovascular disease
Is there anything else I should know?

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

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 performed in my doctor's office?

No, and many hospitals do not offer this test. It is most likely that your sample will be sent to a reference laboratory for testing.
Can I lower my IL-6 level?

Concentrations of IL-6 will decrease with a decrease in inflammation but do not respond to lifestyle changes.

See More Common Questions See Less Common Questions

On This Site

Tests: C-Reactive Protein, Autoantibodies

Conditions: Autoimmune Disorders, Lupus, Rheumatoid Arthritis, Sepsis, Diabetes, Cardiovascular Disease

Elsewhere On The Web

National Cancer Institute: The Immune System
MedlinePlus Medical Encyclopedia: Immune Response
National Institute of Allergy and Infectious Diseases: Immune System Cytokines
National Institute of Arthritis and Musculoskeletal and Skin Diseases: Handout on Health: Rheumatoid Arthritis

View Sources

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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 http://www.hindawi.com/journals/ijr/2011/721608/ through http://www.hindawi.com. Accessed June 2014.

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O'Reilly, S. et. al. (2013 April 12). Interleukin-6: a new therapeutic target in systemic sclerosis? Clinical & Translational Immunology (2013) 2, e4; doi:10.1038/cti.2013.2 [On-line information]. Available online at http://www.nature.com/cti/journal/v2/n4/full/cti20132a.html through http://www.nature.com. Accessed June 2014.

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