From the Guidelines
For a positive ANA with a speckled pattern at 1:640 titer, I recommend ordering specific autoantibody tests to identify the underlying autoimmune condition, including anti-dsDNA, anti-Smith, anti-RNP, anti-SSA/Ro, anti-SSB/La, anti-Jo-1, anti-Scl-70, and anti-centromere antibodies, as suggested by the expert panel in the 2023 Autoimmunity Reviews study 1. These tests are essential in differentiating between various autoimmune diseases such as systemic lupus erythematosus, Sjögren's syndrome, mixed connective tissue disease, and systemic sclerosis.
- The speckled pattern at this high titer is clinically significant and commonly associated with these conditions, though it's crucial to correlate laboratory findings with clinical symptoms for accurate diagnosis 1.
- Additionally, include complement levels (C3, C4), complete blood count, comprehensive metabolic panel, erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, and anti-CCP antibodies in the initial lab workup.
- A urinalysis is also important to assess for kidney involvement, as recommended by the expert panel in the 2023 Autoimmunity Reviews study 1.
- The double-screening strategy using a last-generation SPA in the first place and, subsequently, the CLIFT as the confirmation test for anti-dsDNA testing is recommended, as outlined in the 2023 Autoimmunity Reviews study 1. Some patients may require additional specialized testing based on their specific presentation and initial lab results, and the laboratory report should always detail which method was used, with results obtained with each method reported, as suggested by the expert panel in the 2023 Autoimmunity Reviews study 1.
From the Research
Laboratory Tests for Positive ANA Speckled Pattern 1:640
- The study 2 suggests that a positive ANA speckled pattern 1:640 may be indicative of systemic autoimmune rheumatic diseases (SARDs).
- According to the study 2, ANA titration was significantly associated with the final diagnosis of SARDs at all titres, but the best cut-off was noted at a titre of equal or more than 1:320.
- The following laboratory tests may be considered:
- Complete Blood Count (CBC) to rule out other conditions that may cause a positive ANA result
- Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP) to assess inflammation
- Liver and kidney function tests to evaluate organ involvement
- Complement levels (C3 and C4) to assess immune complex deposition
- Anti-extractable nuclear antigens (anti-ENAs) such as anti-Ro, anti-La, anti-Sm, and anti-RNP to further characterize the autoimmune response
- It is essential to note that the diagnosis of SARDs requires a combination of clinical, laboratory, and radiological findings, and a positive ANA result alone is not sufficient for diagnosis 2.