When to Recheck a Positive ANA Test
A positive ANA test should not be routinely repeated as ANA testing is primarily intended for diagnostic purposes, not for monitoring disease progression. 1, 2
Understanding ANA Testing and Its Purpose
ANA testing serves as a first-level diagnostic tool for Systemic Autoimmune Rheumatic Diseases (SARD), but has significant limitations that affect when and if retesting should occur:
- ANA testing is intended primarily for initial diagnosis, not disease monitoring 1, 2
- ANA can be detected in patients with autoimmune diseases, malignancies, infections, and even healthy individuals 1
- The clinical significance of a positive ANA is highly dependent on pre-test probability and should be interpreted within clinical context 1
Factors That Influence ANA Test Results
Several factors affect the interpretation of ANA results:
- Testing method: Indirect immunofluorescence assay (IIFA) on HEp-2 cells is the reference method 1
- Titer: A screening dilution of 1:160 is generally suitable for adult populations being evaluated for SARD 1, 2
- Pattern: Different patterns have varying associations with specific autoimmune conditions 1, 3
- Population characteristics: Up to 12.9% of healthy individuals may have positive ANA tests 4, 3
When Retesting Might Be Considered
While routine retesting is not recommended, there are specific scenarios where retesting might be appropriate:
1. Clinical suspicion despite initial negative test
- If clinical symptoms strongly suggest an autoimmune disease but initial ANA was negative
- If the initial test was performed using a method other than IIFA on HEp-2 cells 1
2. Development of new symptoms
- When new symptoms develop that suggest evolution of disease or a different autoimmune condition
3. Suspected false positive due to acute infection
- ANA positivity can occur during acute and chronic infections 5
- Consider retesting after resolution of infection if no other symptoms of autoimmune disease are present
What NOT to Do with ANA Testing
- Do not use ANA testing to monitor disease activity or treatment response 1, 2
- Do not repeat testing in asymptomatic individuals with previously positive ANA 6, 7
- Do not order ANA testing without clinical indication, as positive results in the absence of symptoms have limited diagnostic utility 4
Important Considerations for Interpretation
- Pattern and titer are critical for discriminating between ANA-positive healthy individuals and patients with autoimmune diseases 3
- Certain patterns (nuclear homogeneous, nuclear coarse speckled, and nuclear centromeric) appear almost exclusively in patients with autoimmune diseases 3
- Most ANA-positive healthy individuals remain ANA positive over time (72.5% in one study) without developing autoimmune disease 3
- In children with positive ANA but no autoimmune disease at initial evaluation, the vast majority (81%) will not develop an autoimmune condition on follow-up 6
Conclusion for Clinical Practice
ANA testing should be performed once for diagnostic purposes when evaluating for possible autoimmune diseases. The result should be interpreted in the context of clinical symptoms, and specific autoantibody testing should follow based on the pattern, titer, and clinical presentation. Routine retesting of ANA in patients with established diagnoses or in asymptomatic individuals with previously positive results is not recommended and represents unnecessary use of laboratory resources.