ANA

Autoantibodies directed against nuclear antigens, detected by indirect immunofluorescence or immunoassay.

• Negative < 1:40

• Low-Positive: 1:40 to 1:80

• High-Positive > 1:160

Causes

• Systemic autoimmune connective tissue diseases: SLE, Sjögren's disease, scleroderma/systemic sclerosis, autoimmune hepatitis, polymyositis, and rheumatoid arthritis

• Viral infections: Parvovirus B19, EBV, Hepatitis B, Hepatitis C, HIV

• Bacterial infections: Syphilis, Lyme disease, Tuberculosis

• Chronic infections

• Drugs: Procainamide, Hydralazine, Isoniazid, Anti-TNF

• Leukemia

• Lymphoma

• Non-disease factors such as age (positive ANA is clinically insignificant in otherwise healthy people)