The ANA test is the initial screening assay used by clinicians to assess the likelihood that the patient has one of the SARDs. If the ANA is positive, it is common for the clinician to request specific follow-up testing to see if the specific autoantibody(ies) that is/are causing the positive ANA can be identified. Any autoantibody identified may add significantly to the diagnosis of the patient.
The ANA pattern will give the clinician valuable insight into which follow-up testing is appropriate.
- For a speckled ANA pattern, follow-up testing for antibodies directed to the extractable nuclear antigens (ENA) is indicated. ENA testing is most frequently done by ELISA method.
- For a homogeneous ANA pattern, follow-up testing for antibodies to dsDNA is appropriate, with most labs using a fluorescent slide method (CLIF), ELISA, or RIA.
Some laboratories add a comment to the results suggesting appropriate follow-up testing. Using the previous example, "Sample 12345: ANA Positive, Speckled, titer: 1:640; suggest follow-up ENA testing."