From the Guidelines
A positive ANA screen by Immunofluorescence Assay (IFA) is an abnormal result that suggests the presence of antibodies targeting components within the cell nucleus, and further evaluation is necessary to determine its clinical significance. This abnormal result indicates that your immune system may be producing antibodies against your own tissues. While a positive ANA can be associated with autoimmune conditions like systemic lupus erythematosus, Sjögren's syndrome, rheumatoid arthritis, or scleroderma, it's essential to note that some healthy individuals can also have positive results, particularly at lower titers 1. The specificity of ANA detection for SLE is 74.7% (IC 95%: 66.7% - 81.3%) when using a cut-off point of 1:80 by the indirect immunofluorescence test on HEp-2 cells (IFI) 1. Key points to consider include:
- The pattern and titer of the ANA can provide additional diagnostic clues.
- Further evaluation is recommended, including additional blood tests like specific antibody panels (anti-dsDNA, anti-Sm, anti-Ro/SSA), complement levels, and a thorough clinical assessment of your symptoms.
- The ANA test alone is not diagnostic of any specific condition, and its results should be interpreted in the context of your medical history and symptoms to determine if referral to a rheumatologist is appropriate 1. It is crucial to discuss these results with your healthcare provider, who can provide a comprehensive interpretation and guide further management.
From the Research
ANA Screen, IFA
- The ANA (Antinuclear Antibody) screen is a test used to diagnose autoimmune diseases, with a normal value of negative 2.
- A positive ANA test may be seen in non-autoimmune inflammatory diseases, including acute and chronic infections 2.
- The test can also be positive in patients with rheumatoid arthritis and ankylosing spondylitis, especially after treatment with infliximab and etanercept 3, 4.
Causes of Positive ANA Results
- Acute and chronic infections can cause a positive ANA result, especially in children 2.
- Treatment with infliximab and etanercept can also induce a positive ANA result in patients with rheumatoid arthritis and ankylosing spondylitis 3, 4.
- The development of ANA positivity during treatment is not associated with clinical signs of lupus syndrome, but may be correlated with a decrease in inflammatory markers such as ESR and CRP 4.
Interpretation of ANA Results
- The sensitivity and specificity of ANA in diagnosing systemic lupus erythematosus (SLE) are high, even when using sera from patients with multiple medical problems as controls 5.
- However, physicians should be cautious when interpreting ANA results in patients with multiple medical problems who do not have signs or symptoms of SLE or connective tissue diseases 5.
- The presence of ANA can also be seen in healthy individuals, and the prevalence of ANA can vary depending on the population being tested 5, 6.