What this test measures
ELISA / chemiluminescent immunoassay using a mixture of nuclear antigens (typically dsDNA, Sm, RNP, Ro, La, Scl-70, Jo-1, centromere) coated on a microplate. Reports quantitative result (S/CO ratio or index). Less sensitive than IFA — can miss some autoantibody patterns, especially nucleolar and dense fine speckled — and doesn't provide pattern information.
Why it matters
ELISA-based ANA is commonly used in Indian high-throughput labs because it's cheap, fast, and automatable. ACR recommendation is to use IFA on HEp-2 as the gold standard, with ELISA as an acceptable alternative provided positive results are reflexed to IFA for pattern. A negative ELISA in a clinically suspicious patient should still trigger IFA testing.
How to prepare
No fasting required. Disclose biotin supplements (stop 48–72h before — high-dose biotin interferes with many CLIA assays). Note pregnancy, recent infection, recent vaccination.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| ANA ELISA (S/CO ratio or index)[1][2] | Negative: index < 1.0; Borderline: 1.0–2.0; Positive: > 2.0 | < 1.0: negative — CTD unlikely. Doesn't rule out completely; if high clinical suspicion, follow with IFA on HEp-2. | 1.0 – 2.0 (borderline): clinical correlation; consider follow-up IFA. > 2.0 (positive): supports autoimmune disease in suggestive clinical context. Reflex to IFA for pattern + titre, then order specific autoantibodies based on pattern. |
ELISA vs IFA for ANA detection
| Feature | ELISA | IFA (HEp-2) |
|---|---|---|
| Sensitivity | Moderate-High | High (gold standard) |
| Pattern info | No | Yes (homogeneous, speckled, etc.) |
| Turnaround | Fast (1 day) | Slower (1-2 days, manual read) |
| Cost | Cheaper | More expensive |
| Reflex testing | Often to IFA | Direct to specific antibodies |
Frequently asked questions
Which is better: ELISA or IFA?
IFA on HEp-2 cells is the ACR-recommended gold standard — more sensitive and gives pattern information. ELISA is acceptable when used as an initial screen reflexed to IFA on positives. Many Indian labs use ELISA upfront because of throughput and cost.
My ELISA is negative but I have lupus symptoms — what now?
Don't stop at a negative ELISA. ACR recommends IFA testing if clinical suspicion is high — ELISA can miss some autoantibody patterns (especially nucleolar, anti-Ro52, and dense fine speckled).
What does positive ANA ELISA mean?
It suggests presence of one or more autoantibodies. Reflex to IFA for pattern, then order specific antibodies based on clinical picture (anti-dsDNA for SLE; anti-Ro/La for Sjögren; anti-centromere for CREST; anti-Scl-70 for scleroderma; anti-Jo-1 for myositis).
Will biotin affect this?
Yes — high-dose biotin (5–10 mg as in hair / nail supplements) interferes with most CLIA-based ANA assays. Stop biotin for 48–72 hours before testing.
How quickly will I get results?
Most labs report within 24 hours for ELISA. IFA reflex testing adds 1-2 days.
Related Autoimmune / Rheumatology tests
Tests commonly ordered alongside ANA by ELISA Anti Nuclear Antibody screening, or that help interpret an unexpected result.
Sources & references
- ACR — ANA Position Statement · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — ANA Test · accessed 2026-05-30T00:00:00.000Z
- Mayo Clinic Labs — ANA ELISA · accessed 2026-05-30T00:00:00.000Z
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