Antinuclear antibody (ANA) test: Can it diagnose lupus?

An antinuclear antibody (ANA) test is often useful in the evaluation of connective tissue diseases, such as lupus. This blood test detects the presence of certain antibodies made by your immune system. People with lupus typically test positive for antinuclear antibodies. However, a positive ANA blood test doesn't necessarily mean you have lupus. Other conditions may cause a positive antinuclear antibody test, including:

• Scleroderma
• Rheumatoid arthritis
• Sjogren's syndrome
• Hashimoto's thyroiditis
• Autoimmune hepatitis
• Some viral infections
• Type 1 diabetes
• Addison's disease

In addition, certain medications may cause a positive antinuclear antibody test. These include:

• Methyldopa (Aldomet)
• Tumor necrosis factor (TNF) blockers, such as etanercept (Enbrel) and infliximab (Remicade)

If you have a positive antinuclear antibody test, further testing is needed to establish a specific diagnosis. Additional tests to diagnose lupus may include blood counts, kidney and liver assessments, urinalysis, chest X-ray, electrocardiogram (ECG), erythrocyte sedimentation rate test, and other antibody tests that are more specific for lupus.