What Is the ANA Test?
The antinuclear antibody (ANA) test detects antibodies that attack the cell nucleus. It is the standard screening test for lupus and other autoimmune connective tissue diseases. A positive result alone does not diagnose disease — it must be interpreted with symptoms and other tests.
Understanding ANA Titres
| Titre | Interpretation |
|---|---|
| 1:40 | Weakly positive — found in ~30% of healthy people; low clinical significance |
| 1:80 | Borderline positive — low significance unless symptoms present |
| 1:160 | Positive — clinically relevant, especially with symptoms |
| 1:320 or higher | Strongly positive — more likely to be associated with autoimmune disease |
ANA Patterns & Associated Conditions
| Pattern | Associated Antibodies | Conditions |
|---|---|---|
| Homogeneous (diffuse) | Anti-dsDNA, anti-histone | Lupus, drug-induced lupus |
| Speckled | Anti-Sm, anti-SSA/SSB, anti-Scl-70, anti-Jo-1 | Lupus, Sjögren's, scleroderma, myositis |
| Nucleolar | Anti-Scl-70, anti-PM-Scl | Scleroderma, overlap syndromes |
| Centromere | Anti-centromere | Limited scleroderma (CREST syndrome) |
What Next After a Positive ANA?
- Anti-dsDNA and anti-Smith antibodies (specific for lupus)
- Anti-SSA/SSB (Sjögren's syndrome)
- Anti-Scl-70 (scleroderma)
- Anti-Jo-1 (inflammatory myopathy)
- Complement C3 and C4
- Full blood count, renal and liver panel
Most Positive ANAs Are Not Disease
Up to 30% of healthy people have a low-titre positive ANA. A positive ANA without symptoms and a high titre rarely signals autoimmune disease. Context matters enormously.
FAQs
Can ANA be positive without symptoms?
Yes — frequently. A positive ANA alone does not require treatment. Monitor symptoms over time.
Can drugs cause a positive ANA?
Yes — hydralazine, procainamide, isoniazid, and some others cause drug-induced lupus with a positive anti-histone ANA.
Does a positive ANA go away?
In drug-induced cases, yes, after stopping the drug. In autoimmune disease, it typically persists.
Medical Disclaimer: A positive ANA requires clinical interpretation by a rheumatologist alongside specific antibody tests and symptoms.