The ANA test is a type of test widely used to assist in the diagnosis of autoimmune diseases, mainly Systemic Lupus Erythematosus (SLE). Thus, this test aims to detect the presence of autoantibodies in the blood, which are antibodies produced by the body itself and which attack cells and tissues themselves.
This test is based on the fluorescence pattern of the antibodies, making it possible to view it under the microscope and assist 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, which needs to be identified and treated as soon as possible to alleviate symptoms.
What is it for
This FAN exam can help diagnose autoimmune diseases such as:
- Lupus, which is an autoimmune disease characterized by inflation of the joints, skin, eyes and kidneys, for example; Rheumatoid arthritis, in which there is pain, redness and swelling of the joints. Here's how to identify rheumatoid arthritis; Juvenile idiopathic arthritis, in which there is inflammation of one or more joints in children; Autoimmune hepatitis, in which the presence of autoantibodies causes inflammation in the liver. Know the main symptoms of autoimmune hepatitis; Scleroderma, which is an autoimmune disease characterized by increased production of collagen, causing hardening of the skin and joints; Dermatomyositis, which is an inflammatory disease characterized by muscle weakness and dermatological lesions. Learn more about dermatomyositis; Sjögren's syndrome, which is characterized by inflammation of various glands in the body, resulting in dry eyes and mouth, for example. Here's how to recognize the symptoms of Sjogren's Syndrome.
Generally, the doctor may be suspicious of these diseases if the person has symptoms that take a long time to disappear, such as red spots on the body, swelling, constant pain in the joints, excessive tiredness or mild fever, for example.
How the exam is done
This test is very simple, requiring only a small amount of blood to be removed by a trained professional, who is sent to the laboratory for analysis.
Blood collection is usually done at the hospital, but it can also be done at specialized clinics, both for adults and children. In the case of babies, the collection is usually done with a small sting on the foot, without the need to use the needle.
In the laboratory, the examination is carried out by adding a fluorescent dye marked with the antibodies to be identified in the sample. Then, the blood with the labeled dye is placed in a container containing a culture of human cells known as Hep-2 cells, which allows clear visualization of various cell structures and phases of the cell cycle. Thus it is possible to make the diagnosis, since it is made from the fluorescence pattern observed through the microscope.
What preparation is necessary
There is no special type of preparation for the FAN exam, it is only recommended to inform the doctor about the medication being used and possible health problems.
What the results mean
In healthy people, the ANA test is usually negative or non-reactive, 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. Thus, even if it is negative, and according to the symptoms presented, the doctor may order other tests to confirm that it is not an autoimmune disease.
When the result is positive, or reagent, it usually presents values of 1/320, 1/640 or 1/1280. In addition, there is also the positivity pattern that is based on the fluorescence seen under the microscope, which helps to better distinguish the type of disease and which 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, anti-chromatin and anti-histone antibodies is identified, this is indicative of lupus; Nuclear dotted centromeric: it is usually indicative of scleroderma; Fine speckled nuclear: usually indicates Sjogren's syndrome or lupus, depending on the antibody identified; Nuclear speckled thick: 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 nucleus: usually a sign of systemic sclerosis.
These results should always be interpreted and evaluated by a doctor and, in almost all cases, it is necessary to do more tests before confirming the diagnosis.
