Purpose of the Test
The ANA blood test is often used to detect the presence of autoimmune disorders such as Lupus (American Association for Clinical Chemistry). ANA stands for antinuclear antibody, which is an autoantibody that works against the cell nucleus and its contents. Everyone has autoantibodies in low levels, but some people have autoantibodies in higher than normal concentrations. Some of these people can develop autoimmune disorders (WebMD).
In this test, lab technicians determine the pattern and concentration of autoantibodies in the blood. The normal titer of antinuclear antibody is 1:40; higher titers of this autoantibody can indicate that a person is affected by an autoimmune diseases. Some of the conditions that can cause a high ANA titer include Lupus, scleroderma, and rheumatoid arthritis (WebMD).
Why the Test is Ordered
According to the American Association for Clinical Chemistry, the ANA blood test is ordered when someone exhibits the signs and symptoms of an autoimmune disorder. Some symptoms of autoimmune disorders include low-grade fever, joint pain, body aches, skin rashes, and chronic fatigue. When other blood tests cannot rule out more common conditions, doctors may order this test to explore the possibility that the patient has an autoimmune disorder such as Lupus or scleroderma (American Association for Clinical Chemistry).
The test is performed by lab technicians using assays such as ELISA (enzyme-linked immunoabsorbent assay). Technicians report the results of the test as a titer. Low titers are not considered positive, but high titers are indicative of high levels of antinuclear antibodies. This type of result is reported as positive.
The results of this test used to determine an ANA titer are also described as the type of fluorescent patterns that show up on the cells contained in the blood sample.
Specific patterns can indicate specific autoimmune diseases. Lupus and mixed connective tissue disease are associated with a diffuse pattern. Several autoimmune disorders, such as Lupus, rheumatoid arthritis, scleroderma, and polymyositis, are associated with a speckled pattern. Scleroderm and polymyositis are often associated with a nucleolar pattern (American Association of Clinical Chemistry).
American Association for Clinical Chemistry. Lab Tests Online. “ANA.” Retrieved November 29, 2008. Available: American Association for Clinical Chemistry
WebMD. “Antinuclear Antibodies (ANA).” Retrieved November 29, 2008. Available: WebMD