ANA has a very low specificity. This means our test could indicate you may have connective tissue disease, even when you don’t (a false-positive result). Around three in ten people will receive a false positive result. This can lead to unnecessary anxiety and further investigations. One reason for its low specificity is that ANA can be found in other conditions such as liver disease, inflammatory bowel conditions, and chronic infections. Certain drugs, like heart and blood pressure medications, may also increase ANA levels.
Therefore, this test is most suitable when there’s a reasonable suspicion of a connective tissue disease and other more common causes of symptoms have been explored. Results are more clinically significant with ANA titres greater than 1:160.
Although ANA is a good test for ruling out autoimmune disease, there’s a chance you could get a negative result when you do have an autoimmune disease (a false-negative result). False-negative results are less common and occur in about one in twenty cases.