Clinical investigations from the RACP

Investigating the patient with a positive antinuclear antibody

Clinical investigations from the RACP

Investigating the patient with a positive antinuclear antibody

Ian Gotis-Graham

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Abstract

A positive ANA result does not always mean autoimmune disease. Here is how to interpret the test correctly.

Key Points

  • The ANA test is a sensitive test, important in confirming a clinical impression of autoimmune disease. However, a positive result is not specific for autoimmune disease and may not be relevant to the patient’s presenting problems.
  • The correct interpretation of a positive ANA depends on a thorough history and physical examination, careful consideration of the clinical situation, and appropriate laboratory investigations.
  • The ANA titre and staining pattern are less important in determining the relevance of the test result.
  • A positive ANA may be due to early, undifferentiated autoimmune disease.
  • A positive ANA can be found in normal healthy individuals. The incidence of a positive ANA increases with age.