Antinuclear antibody test: A test for unusual antibodies that are directed against structures within the nucleus of the cell. Antinuclear antibodies (ANAs) indicate the possible presence of autoimmunity.
The fluorescent antinuclear antibody test (FANA) was designed by George Friou, M.D. in 1957. It is done on a blood sample. The antibodies in serum are exposed to cells and then one determines whether antibodies are present that react with parts of the nucleus of the cell. It is a sensitive screening test used to detect autoimmune diseases.
ANAs are found in patients with a number of autoimmune diseases, such as systemic lupus erythematosus, Sjogren syndrome, rheumatoid arthritis, polymyositis, scleroderma, Hashimoto thyroiditis, juvenile diabetes mellitus, Addison disease, vitiligo, pernicious anemia, glomerulonephritis, and pulmonary fibrosis. ANAs can also be found in patients with chronic infections and cancer. Many medications including procainamide (PROCAN SR), hydralazine, and dilantin can stimulate the production of ANAs.
ANAs are present in approximately 5% of the normal population, usually in low titers (low levels). These persons have no disease. ANA titers lower than 1:80 are unlikely to be significant. Even higher titers are insignificant over the age of 60. Ultimately, the ANA result must be interpreted in the specific context of the symptoms and other test results for the patient. It may or may not be significant in an individual.