The ANA test is a type of test widely used to assist in the diagnosis of autoimmune diseases, especially systemic lupus erythematosus (SLE). Therefore, this test aims to detect in the blood the presence of antinuclear antibodies, which are antibodies produced by the body and that attack your own cells and tissues.
This test is based on the fluorescence pattern of the antibodies and can be viewed under a microscope and assists in the diagnosis of various diseases. Although it is normal to have a low ANA test result, when this number is very high, it may mean that there is an autoimmune disease that needs to be identified and treated as soon as possible to relieve symptoms.
What an ANA test evaluates
This ANA test can help diagnose autoimmune diseases such as:
- Lupus, is n autoimmune disease characterized by joint, skin, eye and kidney inflation, for example;
- Rheumatoid arthritis, provokes pain, redness and swelling of the joints;
- Juvenile idiopathic arthritis, there is inflammation of one or more joints in children;
- Autoimmune hepatitis, where there is presence of antinuclear antibodies that cause inflammation in the liver;
- Scleroderma, which is an autoimmune disease characterized by increased collagen production, causing hardening of the skin and joints;
- Dermatomyositis, is an inflammatory disease characterized by muscle weakness and dermatological lesions;
- Sjögren's syndrome, which is characterized by inflammation of various glands in the body.
Generally, a doctor may be wary of these conditions if the person has symptoms that take a long time to disappear, such as red spots on the body, swelling, constant joint pain, excessive tiredness or mild fever, for example.
How is the test done
This test is very simple, it is only necessary to draw a small amount of blood in a certified laboratory and with qualified professional. The collected blood is then sent to the laboratory for analysis.
Blood collection is usually done at the hospital, but can also be done at specialist clinics for both adults and children. Foe babies, the collection is usually done with a small prick in the foot, without the need to use a needle.
In the laboratory, the test is made by adding a fluorescent dye labeled with the antibodies to be identified in the sample. The labeled dye blood is then placed in a container containing a known human cell culture with Hep-2 cells, which allows clear visualization of various cell structures and phases of the cell cycle. Therefore, it is possible to make the diagnosis, since it is done from the fluorescence pattern observed through the microscope.
What is the necessary preparation for a ANA test
There is no special preparation for a ANA test, it is only recommended you inform your doctor about the medication you are using and possible health problems.
What do the results indicate
In healthy people the ANA test is usually negative or nonreactive, with values such as 1/40, 1/80 or 1/160. However, this does not mean that whenever it is negative there is no autoimmune disease. Therefore, even if the result is negative, but considering the symptoms you present, the doctor may order further tests to confirm that it is not an autoimmune disease.
When the result is positive, or reagent, usually the values are about 1/320, 1/640 or 1/1280. In addition, there is the positivity pattern which is based on the fluorescence seen under the microscope, which helps to better distinguish the type of disease and may include:
- Homogeneous nuclear: may indicate the presence of lupus, rheumatoid arthritis or juvenile idiopathic arthritis, depending on the antibody identified. If the presence of anti-DNA antibody, anti-chromatin and anti-histone is identified, it is indicative of lupus;
- Centromeric dotted nuclear: usually indicative of scleroderma;
- Fine dotted nuclear: usually indicates Sjögren's syndrome or lupus, depending on the identified antibody;
- Coarse dotted nuclear: lupus, rheumatoid arthritis or systemic sclerosis according to the identified antibodies;
- Fine dotted cytoplasmic: may be polymyositis or dermatomyositis;
- Continuous nuclear membrane: may indicate autoimmune hepatitis or lupus;
- Dotted Nucleolar: Usually a sign of systemic sclerosis.
These results should always be interpreted and evaluated by a physician and in almost all cases further testing is required before confirming the diagnosis.