Monday, March 16, 2015

ANA (Antinuclear Antibodies)

Heterogeneous antibodies to nuclear antigens (DNA and RNA, histone and nonhistone proteins). Antinuclear antibody is measured in patient's serum by layering serum over human epithelial cells and detecting the antibody with fluorescein-conjugated polyvalent anti-human immunoglobulin. 


Normal Range: < 1:20 


Elevated in: 1/3-3/4 of patients over age 65 (usually in low titers), systemic lupus erythematosus (98%), drug-induced lupus (100%), Sj?gren's (80%), rheumatoid arthritis (30-50%), scleroderma (60%), mixed connective tissue disease (100%), Felty's syndrome, mononucleosis, hepatic or biliary cirrhosis, hepatitis, leukemia, myasthenia gravis, dermatomyositis, polymyositis, chronic renal failure. 

 
Additional: A negative ANA test does not completely rule out SLE, but alternative diagnoses should be considered. Pattern of staining of ANA may give some clues to diagnoses, but since the pattern also changes with serum dilution, it is not routinely reported. Only the rim (peripheral) pattern is highly specific (for SLE). Not useful as a screening test. Should be used only when there is clinical evidence of a connective tissue disease

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