Antinuclear Antibody Test
(ANA)

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Medical Author:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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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.

What are autoimmune diseases?

Autoimmune diseases are conditions in which there is a disorder of the immune system characterized by the abnormal production of antibodies (auto-antibodies) directed against the tissues of the body. Autoimmune diseases typically feature inflammation of various tissues of the body. ANAs are found in patients with a number of different autoimmune diseases, such as systemic lupus erythematosus, Sjogren's syndrome, rheumatoid arthritis, polymyositis, scleroderma, Hashimoto's thyroiditis, juvenile diabetes mellitus, Addison disease, vitiligo, pernicious anemia, glomerulonephritis, and pulmonary fibrosis. ANAs can also be found in patients with conditions that are not considered classic autoimmune diseases, such as chronic infections and cancer.