From the Guidelines
A positive ANA screen with reflex indicates the presence of antinuclear antibodies in your blood, which may suggest an autoimmune disorder, and you should consult with a rheumatologist for further evaluation as this is not a definitive diagnosis on its own. The test works by detecting antibodies that target components within the cell nucleus, and the pattern and titer (concentration) of these antibodies provide important diagnostic clues 1. According to recent recommendations, a positive ANA result should be used to select additional assays to assess other parameters, such as anti-ENA antibodies, to help determine the specific autoimmune disorder 1.
Key Considerations
- The 1:160 dilution is recommended as the cut-off point for ANA detection in unselected populations, as it increases the positive likelihood ratio and diagnostic performance 1.
- The EULAR/ACR 2019 classification criteria recommend ANA detection using the IFI or a solid-phase ANA screening immunoassay (SPA) with at least equivalent performance 1.
- The laboratory report should always detail which method was used for ANA detection, and if several methods are used, the results obtained with each method should be reported 1.
Next Steps
- Consult with a rheumatologist for further evaluation and to determine the need for additional specific antibody tests.
- Track any symptoms you're experiencing, such as joint pain, skin rashes, fatigue, or fever, as this information will be valuable for your doctor.
- No immediate medication is required based solely on this result, as many healthy individuals can have positive ANA tests without disease 1.
From the Research
Interpretation of ANA Screen with Reflex (ANAG) Positive
- A positive ANA screen with reflex (ANAG) result indicates the presence of antinuclear antibodies in the blood, which can be associated with various autoimmune diseases, including Systemic Lupus Erythematosus (SLE) 2, 3.
- The positive predictive value of a positive ANA test result for lupus is relatively low, ranging from 2.1% to 9.1% for any antinuclear antibody-associated rheumatic disease 4.
- The clinical utility of a positive ANA test result depends on the clinical context and the presence of other symptoms and laboratory findings 2, 4.
Association with Systemic Lupus Erythematosus (SLE)
- SLE is a prototypic autoimmune disease characterized by the presence of antinuclear antibodies, which can form immune complexes that mediate pathogenesis 3.
- The presence of anti-double-stranded DNA antibodies is a specific marker for SLE, and their levels can fluctuate widely, reflecting disease activity 3.
- Other autoantibodies, such as anti-Ro/SS-A and anti-La/SS-B, can also be useful predictors for the diagnosis of SLE, especially among patients who are positive for ANA and negative for anti-dsDNA 5.
Clinical Implications
- A positive ANA screen with reflex (ANAG) result should be interpreted in the context of the patient's clinical presentation and other laboratory findings 2, 4.
- Further testing, such as anti-double-stranded DNA antibody testing and extractable nuclear antigen (ENA) antibody testing, may be necessary to confirm the diagnosis of SLE or other autoimmune diseases 3, 5.
- The presence of a positive ANA test result does not necessarily indicate the presence of an autoimmune disease, and clinical correlation is essential to determine the significance of the result 4.