What is an antinuclear antibody test?

(November 14, 2011)

What causes a Positive ANA Test?

ANA testing, medically termed as being anti nuclear anti body testing, is a medical test that is used to screen for autoimmune disorders in an individual. It may also be used to diagnose certain specific auto immune disorders such as System Lupus Erythematosus (SLE). The reason a doctor will call for the ANA test to be performed will generally be on the basis of autoimmune disorder symptoms being rather prominent. Some of the more common symptoms that are likely to be present at this point include joint pain, fatigue, low grade fever as well as the development of unexplained rashes all over the body.

The main causes of positive ANA test results indicates that the body is affected by some autoimmune condition or the other, whether known or unknown. Results of positive ANA tests will be dependent on the clusters and patterns shown up under the microscope during the test. These different patterns are associated with a number of autoimmune disorders and will require further and more specific testing in order to identify the primary problem. Some of the causes of false positive ANA tests include a variety of drugs and other infections like non viral hepatitis which is chronic as well as primary biliary cirrhosis.

How long do ANA Test results take?

ANA tests, medically termed as being anti nuclear anti body tests, are primarily carried out in order to ascertain if an individual suffers from autoimmune disorders – with the most common one being systemic lupus erythematosus or SLE. Some of the signs and symptoms that are the common in autoimmune disorders include joint pain, low grade fever, fatigue as well as the development of unexplained rashes all over the body. It is when these symptoms are noticed that the medical professional handling the case is likely to call for an ANA test to be performed.

ANA test results and ANA test results interpretation will depend on the patterns that show up under a microscope. These patters will tell the technician or doctor performing the test exactly what kind of autoimmune disorder is affecting the patient. Positive results indicate that an autoimmune disorder is present despite the fact that, in all likelihood, you are going to have to have more specific testing done in order find out the exact autoimmune condition. It is also possible for the tests to show positive results despite being affected by no known autoimmune disease. Some other conditions that are also likely to test positive when performing an ANA test include Sjogren Syndrome and scleroderma.

ANA Testing

Antinuclear antibody (ANA) test is a sensitive screening test used to detect autoimmune diseases. ANA test is also sometimes called as FANA (fluorescent antinuclear antibody test). The antinuclear antibody test identifies the presence of antinuclear antibodies (ANA) in the blood. Antinuclear antibodies are a group of special antibodies produced by the patient. Antinuclear antibodies (ANAs) are unusual antibodies, detectable in the blood, that have the capability of binding to the nucleus of cells. Auto antibodies, instead of acting against foreign invaders as normal antibodies do, attack the body's own cells, causing various symptoms of auto immune disorders such as organ or tissue inflammation, fatigue, and joint pain.

An antinuclear antibody test is most commonly conducted for the diagnosis of an autoimmune disorder known as systemic lupus erythematosus (SLE). Antinuclear antibodies can provide an indication for doctors to consider the possibility of autoimmune illness.

There are other tests which can be ordered along with the ANA test for the accurate screening of autoimmune disorders. Laboratory tests such as C-reactive protein are also associated with the presence of inflammation. These tests help rule out a diagnosis of other autoimmune disorders. The ANA test is ordered when a patient shows symptoms associated with autoimmune disorders such as low-grade fever, joint pain, fatigue, and/or unexplained rashes that may change over time.

The ANA tests are performed using different assays such as ELISA or indirect immunofluorescence. The results of the test are reported as a titer of immunofluorescence pattern. Different patterns are associated with different auto immune disorders.

An elevated concentration of antinuclear antibodies indicates the results are positive and the increased titer value would be as 1:320, whereas low level titers indicate negative results. Positive ANA tests do not need to be repeated. Changes in the ANA titer do not correlate with disease activity. The presence of ANA in the blood may be due to systemic lupus erythematosus, collagen vascular disease, myositis, rheumatoid arthritis and Sjogren's syndrome.

An ANA report consists of three parts:  

•    Results: Whether positive or negative
•    If positive, a titer is determined and reported
•    If positive, the pattern of fluorescence is reported.

If the patient is detected with SLE, there are two subset tests such as anti-dsDNA and anti-SM that should be ordered to confirm that the condition is SLE. The ANA results are just one factor in diagnosis and must be considered together with the patient's clinical symptoms and other diagnostic tests. The ANA test is complex, but the results and the specific subset test results can give physicians valuable diagnostic information.

However, a positive ANA test result may also be drug-induced. For instance, procainamide and hydralazine are certain medications known to promote the production of ANAs. In this case, the elevated levels of ANA may give false positive results which are not related to any disease.