From the Guidelines
A positive Antinuclear Antibody (ANA) test can be caused by conditions other than Systemic Lupus Erythematosus (SLE), including other autoimmune diseases and healthy individuals.
Conditions that can cause a positive ANA test without SLE
- Other autoimmune diseases, such as inflammatory myopathies, Sjögren’s syndrome, and mixed connective tissue disease 1
- Healthy individuals, with up to 25% of sera from apparently healthy individuals being ANA positive, depending on demographics and assay variables 1
Important considerations
- The indirect immunofluorescence assay (IIFA) is the gold standard technique for ANA detection, but it lacks specificity and can yield false positives 1
- A positive ANA test should be interpreted in the context of clinical suspicion and other laboratory tests, such as anti-dsDNA and anti-ENA antibodies 1
- The pattern and highest dilution of ANA reactivity should be reported, and testing for anti-dsDNA antibodies is advised when there is clinical suspicion of SLE 1
From the Research
Conditions Causing a Positive ANA Test without SLE
A positive Antinuclear Antibody (ANA) test can be caused by several conditions other than Systemic Lupus Erythematosus (SLE). Some of these conditions include:
- Acute and chronic infections, as identified in a study published in the Journal of immunoassay & immunochemistry 2
- Primary antiphospholipid syndrome (APS), as found in a multicenter retrospective study published in Joint bone spine 3
- Non-autoimmune inflammatory diseases, as mentioned in the study published in the Journal of immunoassay & immunochemistry 2
- Fibromyalgia, as diagnosed in 14 out of 44 patients in a study published in the Journal of clinical rheumatology 4
- Seronegative rheumatoid arthritis, as diagnosed in 4 out of 44 patients in the same study 4
- Myasthenia gravis, as diagnosed in 1 out of 44 patients in the study published in the Journal of clinical rheumatology 4
Other Factors to Consider
Other factors that can contribute to a positive ANA test without SLE include:
- Widespread pain, which was the most common reason for ordering ANA testing in a retrospective study published in The American journal of medicine 5
- Low pretest probabilities for ANA-associated rheumatic disease, which can lead to unnecessary testing and a poor predictive value of a positive ANA test, as found in the study published in The American journal of medicine 5
- The presence of other antibodies, such as anti-Ro antibodies, which can be associated with ANA negative SLE, as reported in a case study published in the Asian Pacific journal of allergy and immunology 6