Antinuclear Antibody(ANA) Test

What is this test?


This blood test is done to help your healthcare provider find out if you have an autoimmune disease. Your immune system is your body’s defense system. It protects you against foreign invaders like viruses and bacteria. In some cases, your immune system can become confused. It can think that normal cells in your body are foreign invaders. When that happens, your body can make proteins called antibodies that attack your own cells.

When antibodies attack cells in your body, they cause swelling and redness known as inflammation. Antinuclear antibodies attack normal proteins in the center structure (nucleus) of your body’s cells. Antinuclear antibodies are found in many autoimmune diseases. These include lupus, scleroderma, and rheumatoid arthritis. 


Why do I need this test?


Your healthcare provider may order this test if you have symptoms of an autoimmune disease. Common symptoms of autoimmune diseases that may stem from antinuclear antibodies include:

  • Fever

  • Joint pain

  • Weight loss

  • Skin rash

  • Tiredness


What other tests might I have along with this test?


Finding antinuclear antibodies in your blood tells your healthcare provider only that you may have an autoimmune disease. It doesn’t tell him or her which disease you have. Your provider may order other tests depending on your symptoms and your physical exam. 


What do the test results mean?


Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. A positive test for ANA does not mean you have an autoimmune disease. The test finds small amounts of these antibodies in up to 15% of healthy people. Antinuclear antibodies are measured in titers. A titer above 1:160 is a positive test result.

 A positive result may mean:

  • You have systemic lupus erythematosus or SLE. About 95% of people with this autoimmune disease test positive for antinuclear antibodies.

  • You have another type of autoimmune disease.

  • You have a short-term condition, like an infection, that’s causing your antinuclear antibodies to go up.

  • You are one of the 15% of normal people who have positive antinuclear antibodies without any disease.


How is this test done?


The test requires a blood sample, which is drawn through a needle from a vein in your arm.


What might affect my test results?


Many conditions can trigger a positive antinuclear antibody test even without an autoimmune disease. Conditions that may cause a “false positive” test include:

  • Being older than 65

  • Having cancer

  • Taking certain medicines

  • Having a viral infection

  • Having a long-term infection