What does a positive Antinuclear Antibody (ANA) result indicate?

From the Guidelines

A positive ANA result indicates the presence of autoantibodies and suggests an autoimmune disorder, but it is not definitive for a specific condition and requires further testing and evaluation by a rheumatologist. This result should be interpreted with caution, considering the clinical context and the titer level of the ANA result, as a low-positive result can be found in healthy individuals without disease 1.

Key Considerations

• The ANA test is sensitive but not specific, and a positive result can be associated with various systemic rheumatologic disorders 1.
• The EULAR/ACR 2019 classification criteria recommend a positive ANA result as an entry criterion for systemic lupus erythematosus (SLE) diagnosis, but this should be used with caution in clinical practice due to the relatively low specificity of ANA detection at a titer ≥1:80 1.
• In unselected populations, the 1:160 dilution should be used as the cut-off point for ANA detection to increase specificity 1.
• Additional assays, such as anti-ENA testing, should be used to assess other parameters when ANA results are positive, and the choice of these assays should be determined by the clinical context 1.

Next Steps

• Patients with a positive ANA result should be referred to a rheumatologist for further evaluation and testing to determine the presence of a specific autoimmune disease, such as lupus, Sjögren's syndrome, or scleroderma 1.
• Confirmatory testing of anti-ENA autoantibodies is recommended when ANAs are positive during diagnosis 1.
• A healthy lifestyle with adequate rest, balanced nutrition, and stress management is essential, as these factors can influence autoimmune activity, and regular monitoring is necessary even without current symptoms, as autoimmune conditions can develop over time 1.

From the Research

Ana Positive Result

• A positive ANA (antinuclear antibody) test result can indicate the presence of an autoimmune disease, such as systemic lupus erythematosus (SLE) 2, 3, 4, 5, 6
• The clinical utility of a positive ANA test result is limited, with a positive predictive value of 2.1% for lupus and 9.1% for any antinuclear antibody-associated rheumatic disease 3
• ANA-specific antibodies, such as anti-SSA, anti-dsDNA, and anti-Sm, can be useful in making a diagnosis in ANA-negative patients with clinical suspicion 2, 4, 5, 6
• The presence of anti-ENA antibodies, especially anti-Ro/SS-A, can be a useful predictor for the diagnosis of SLE, primarily among patients who are positive for ANA and negative for anti-dsDNA 6
• ANA patterns, such as speckled and homogenous, can be associated with specific autoimmune diseases, but testing for ANA-specific antibodies cannot be gated on ANA patterns 2
• The interpretation of ANA test results requires consideration of the disease context, antibody level, and titre-specific information, as well as the limitations of the assay used 5

ANA Test Results

• ANA test results can be positive in patients with various autoimmune diseases, including SLE, Sjogren's syndrome, and mixed connective tissue disorder 2, 4, 6
• The sensitivity and specificity of ANA tests can vary depending on the assay used and the population being tested 3, 5
• ANA test results can be influenced by factors such as age, sex, and ethnicity, and can be affected by the presence of other autoimmune diseases or infections 4, 5

Clinical Diagnosis

• A positive ANA test result should be interpreted in the context of clinical symptoms and other laboratory results to make a diagnosis of an autoimmune disease 2, 3, 4, 5, 6
• The diagnosis of SLE and other autoimmune diseases requires a combination of clinical, laboratory, and immunological criteria 4, 5, 6
• The presence of anti-ENA antibodies and other ANA-specific antibodies can be useful in supporting a diagnosis of SLE or other autoimmune diseases 2, 4, 5, 6