Semi-Quantitative Indirect Fluorescent Antibody/Qualitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Multiplex Bead Assay/Qualitative Immunoblot
- Initial screen for autoimmune connective tissue diseases
- One or more reflexive tests may be added, depending on ANA pattern detected (see ANA IFA Reflex Testing Algorithm)
Semi-Quantitative Indirect Fluorescent Antibody
Qualitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Indirect Fluorescent Antibody
Qualitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Indirect Fluorescent Antibody/Semi-Quantitative Multiplex Bead Assay
Antinuclear antibody (ANA) testing is used in the diagnostic evaluation of various autoimmune diseases, including connective tissue diseases such as systemic lupus erythematosus (SLE), Sjögren syndrome, and systemic sclerosis (SSc). Initial testing for autoimmune connective tissue diseases (also referred to as systemic autoimmune rheumatic diseases, or SARDs) should include C-reactive protein (CRP), ANA, rheumatoid factor, and cyclic citrullinated peptide antibodies. Follow-up or confirmatory testing for positive ANA may be guided pattern(s) observed and/or patient’s clinical presentation.
Autoimmune connective tissue diseases may present with similar features, making diagnosis difficult. Possible diagnoses may include:
- Inflammatory myopathies
- Mixed connective tissue disease
- Sjögren syndrome
- Undifferentiated connective tissue disease
ANA with reflex by immunofluorescent assay (IFA) (based on ANA patterns) may help in distinguishing between diseases.
Antigen/antibody complexes affect a variety of organs in connective tissue diseases, which frequently leads to a multisystem disease presentation. ANA antibodies are the most common antibodies and may precede the onset of connective tissue disease. While certain antibodies may show specificity for certain diseases (eg, SSA 52, SSA 60, and SSB antibodies for Sjögren syndrome), ANA antibodies are not specific for connective tissue disease and may also be associated with infectious diseases, cancers, other autoimmune disorders (eg, autoimmune liver disease), and advanced age, and may even be present in healthy patients.
Dual or mixed pattern may indicate disease overlap. Visit the International Consensus on Antinuclear Antibody Patterns website for additional information about pattern and disease associations.
- Dual or mixed patterns will not be reflexed; additional testing for dual or mixed patterns should be determined by the ordering physician
- A negative ANA by IFA test does not rule out the presence of connective tissue disease