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ANTINUCLEAR ANTIBODY TEST (ANA)
What
is antinuclear antibody (ANA)?
Antibodies are substances that are produced by the immune system of the body
to fight the germs causing infection.
Sometimes there is abnormal production of antibodies (auto-antibody) that attack
the body’s own body systems and tissues leading to autoimmune diseases
such as systemic lupus erythematosus (SLE), Rheumatoid Arthritis (RA), scleroderma,
Sjogren’s syndrome etc.
Antinuclear antibodies (ANA) are unusual antibodies that are directed against
the structures within the nucleus of the cells. Presence of ANA indicates the
presence of autoimmune disease.
In
what other conditions can ANA test be positive?
ANA test may be positive in persons taking antihypertensives (blood pressure
lowering agents) and anticonvulsants (drugs to treat epilepsy) such as procainamide,
hydralazine and phenytoin. These are referred to as drug induced ANA
positive and does not necessarily indicate the presence of disease.
ANA can be produced in patients with lung diseases such primary
pulmonary fibrosis, pulmonary hypertension, Gl diseases such
as ulcerative colitis, Crohn’s disease, primary biliary cirrhosis, alcoholic
liver disease; blood diseases such as ITP, hemolytic anemia;
skin diseases such as psoriasis and pemphigus as well as in
elderly and those persons with a family history of rheumatic diseases.
How
is the ANA test performed?
ANA test is performed using a blood test. The antibodies in the blood are exposed
in the laboratory to cells. It is then tested whether these antibodies are reactive
to various parts of the nucleus of cells.
Last created on 15-12-03
Last updated on 18-11-2006