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Antibody Tests for Lupus

Overview

Antibody tests are a set of blood tests that check for specific antibodies to help clarify the diagnosis of lupus. They may also be called an ENA (extractable nuclear antibody) screen. They include:

  • Anti-dsDNA (antibodies to DNA).
  • Antinuclear antibody (ANA)
  • 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 or if the ANA test is negative but lupus is strongly suspected.

  • 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 women with lupus who are considering pregnancy. If a woman who has these antibodies becomes pregnant, she may need more careful monitoring of the fetus, 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 titres 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.

Credits

Adaptation Date: 2/24/2022

Adapted By: Alberta Health Services

Adaptation Reviewed By: Alberta Health Services

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