Patient Test Information


Also known as:


Formal name:


Related tests:

C-Reactive Protein, Autoantibodies

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?


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.

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.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

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

No test preparation is needed.

  1. 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.

  2. 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.