An antinuclear antibody (ANA) test measures the amount and pattern of antibodies in your blood that work against your own body (autoimmune reaction).
The body's immune system normally attacks and destroys foreign substances such as bacteria and viruses. But in disorders known as autoimmune diseases, the immune system attacks and destroys the body's normal tissues. When a person has an autoimmune disease, the immune system produces antibodies that attach to the body's own cells as though they were foreign substances, often causing them to be damaged or destroyed. Rheumatoid arthritis and systemic lupus erythematosus are examples of autoimmune diseases.
An ANA test is used along with your symptoms, physical examination, and other tests to find an autoimmune disease.
Why It Is Done
An ANA test is done to help identify problems with the immune system, such as:
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
If there are more antibodies in the blood than normal, the test is positive. When the test is positive, most labs do other tests right away to look for the cause. These tests can find out which antibodies are in the blood in higher amounts than normal.
Sometimes ANA test results can be positive when a person is healthy. Though the test is positive, the level of antibodies is usually low.
Some healthy people can have an increased amount of ANA in their blood. For instance, this can happen in some people with a family history of autoimmune disease. ANA levels can also increase as a person ages.
Autoimmune diseases can't be diagnosed by the results of the ANA test alone. Other tests are needed to help identify diseases such as lupus or rheumatoid arthritis.
Author: Healthwise Staff Medical Review: Anne C. Poinier MD - Internal Medicine Martin J. Gabica MD - Family Medicine E. Gregory Thompson MD - Internal Medicine Kathleen Romito MD - Family Medicine Adam Husney MD - Family Medicine
Medical Review:Anne C. Poinier MD - Internal Medicine & Martin J. Gabica MD - Family Medicine & E. Gregory Thompson MD - Internal Medicine & Kathleen Romito MD - Family Medicine & Adam Husney MD - Family Medicine
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