Antibody Tests for Lupus

Antibody tests are a set of blood tests that check for specific antibodies to help clarify the diagnosis of lupus. They include:

• Antinuclear antibody (ANA).
• Anti-dsDNA (antibodies to DNA).
• Anti-RNP.
• Anti-Smith (Sm).
• Anti-SS-A (also called Ro).
• Anti-SS-B (also called La).

These antibody tests are often positive in lupus and can provide support for a diagnosis if the clinical criteria are unclear.

• Anti-SS-A (Ro) and anti-SS-B (La) antibodies are not specific for lupus and are found commonly in Sjögren's syndrome. But these tests are useful in helping anyone with lupus who is considering pregnancy. If someone who has these antibodies becomes pregnant, more careful monitoring of the fetus may be needed, since these antibodies are associated with a higher risk of the baby being born with neonatal lupus syndrome or a heart defect called congenital heart block.
• High titers of anti-dsDNA are usually seen only in people who have lupus.
• A positive anti-Sm test is a specific marker for lupus.

Anti-dsDNA tests can be repeated at intervals to monitor how the disease is progressing.