From the Guidelines
The initial approach for an autoimmune screen in a patient like Anatoly should include antinuclear antibody (ANA) testing with a cut-off point of 1:160, as this provides a better balance between sensitivity and specificity, according to the most recent guidelines 1. When interpreting ANA results, it's crucial to consider the clinical context and the pattern of fluorescence, as different patterns can suggest different autoimmune diseases.
- The ANA test should be accompanied by pertinent clinical information to help the laboratory assess the results and decide on subsequent studies.
- Additional first-line tests may include complete blood count, comprehensive metabolic panel, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), as well as rheumatoid factor, anti-cyclic citrullinated peptide antibodies, complement levels (C3, C4), and urinalysis.
- Based on clinical suspicion, more specific antibody tests may be ordered, such as anti-double stranded DNA, anti-Smith, anti-Ro/SSA, anti-La/SSB, anti-neutrophil cytoplasmic antibodies, and anti-cardiolipin antibodies.
- The method used for ANA detection should be reported, and the results should be interpreted in the context of the patient's clinical presentation, as false positives can occur and some patients with autoimmune disease may initially test negative, as highlighted in previous recommendations 1.
- It's also important to note that the laboratory should specify the methods used for detecting ANA and that the results should be reported with the pattern and the highest dilution to demonstrate reactivity, as suggested by international recommendations 1.
- Testing should be performed before initiating immunosuppressive therapy, which could affect results, and the pattern and titer of ANA can guide further testing, with high titers (≥1:160) being more clinically significant.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Initial Approach for Autoimmune Screen
The initial approach for an autoimmune screen in a patient like Anatoly involves detecting autoantibodies associated with systemic rheumatic diseases.
- Autoantibodies directed to intracellular antigens can be detected in many systemic rheumatic diseases 2.
- The presence of antinuclear antibodies (ANA) is a key indicator of autoimmune diseases such as systemic lupus erythematosus (SLE), Sjögren's syndrome, scleroderma, and polymyositis/dermatomyositis 2, 3.
- Other autoantibodies, including anti-dsDNA, anti-Ro/SS-A, and anti-La/SS-B, can also be detected in patients with autoimmune disorders 3, 4.
Detection Methods
Various methods can be used to detect autoantibodies, including:
- Indirect immunofluorescence technique 3
- Enzyme-linked immunosorbent assay (ELISA) 3
- Counterimmunoelectrophoresis 5
- Immuno and western blotting 5
- AtheNA Multi-Lyte ANA II Plus Test System on a Bio-Plex Array Reader (Luminex200) 4
Interpretation of Results
The results of autoantibody tests should be carefully considered and interpreted in clinical context 2.
- The presence of autoantibodies can indicate an increased risk of developing autoimmune diseases 4.
- The sensitivity and specificity of different autoantibody tests can vary, and rigorous standardization of commercial reagents and analytical procedures is necessary 5.
- External quality assessment (EQA) programs and complete definition of operative protocols adjusted to the sensitivity and specificity of the various methods are also essential 5.