Antinuclear Antibody Test (ANA) Information on MedicineNet.com

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Antinuclear Antibody Test
(ANA)

Medical Author: William C. Shiel Jr., MD, FACP, FACR

What are antinuclear antibodies?

We normally have antibodies in our blood that repel invaders into our body, such as virus and bacteria microbes. Antinuclear antibodies (ANAs) are unusual antibodies, detectable in the blood, that have the capability of binding to certain structures within the nucleus of the cells. The nucleus is the innermost core within the body's cells and contains the DNA, the primary genetic material. ANAs are found in patients whose immune system may be predisposed to cause inflammation against their own body tissues. Antibodies that are directed against one's own tissues are referred to as auto-antibodies. The propensity for the immune system to work against its own body is referred to as autoimmunity. ANAs indicate the possible presence of autoimmunity and provide, therefore, an indication for doctors to consider the possibility of autoimmune illness.

How is the ANA test designed? What is it for?

The ANA test was designed by Dr. George Friou in 1957. The ANA test is performed using a blood sample. The antibodies in the serum of the blood are exposed in the laboratory to cells. It is then determined whether or not antibodies are present that react to various parts of the nucleus of cells. Thus, the term anti-"nuclear" antibody. Fluorescence techniques are frequently used to actually detect the antibodies in the cells, thus ANA testing is sometimes referred to as fluorescent antinuclear antibody test (FANA). The ANA test is a sensitive screening test used to detect autoimmune diseases.

Next: What are autoimmune diseases? »

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