https://resources.lupus.org/entry/the-antinuclear-antibody-test

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The antinuclear antibody (ANA) test

Lupus Foundation of America

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The body uses antibodies to attack and neutralize foreign substances, such as bacteria and viruses. The antibodies your body makes against its own normal cells and tissues play a large role in lupus. 

97% of people with lupus will test positive for ANA

Many of these antibodies are found in a panel or group of tests that are ordered at the same time. 

The test you will hear about most is called the antinuclear antibodies test, referred to as the ANA test.

Antinuclear antibodies connect or bind to the nucleus or command center of the cell. This process damages and can destroy the cells. While the antinuclear antibody is not a specific test for lupus, it is sensitive and does detect the antibodies that are present in 97 percent of people with the disease.

The ANA can be positive in people with other illnesses or positive in people with no illness, so simply having a positive ANA test does not necessarily mean you have lupus. Test results can also fluctuate in the same person. When a positive ANA is accompanied by several other criteria that doctors look for in diagnosing lupus, it is often a strong indication for doctors to consider lupus. Doctors trying to diagnose lupus often look for a number of other antibodies as well.