What this test measures
Anti-Nuclear Antibodies (ANA) are autoantibodies your immune system makes against components of the cell nucleus — DNA, histones, ribonucleoproteins, and other nuclear antigens. ANA testing detects whether such antibodies are present in your blood, and at what concentration (titre).
This specific test is the ELISA/immunoassay format — a quantitative screen, typically reported as units/mL with a positive/negative cut-off. The companion test (ANA by IFA — indirect immunofluorescence on HEp-2 cells) gives a titre (1:80, 1:160, etc.) and pattern (homogeneous, speckled, nucleolar, centromere) and is considered the gold standard for confirmation. Many Indian labs use ELISA as the first screen and reflex to IFA when positive.
Why it matters
ANA is the entry point into the workup of suspected autoimmune disease. Doctors order it when patients have unexplained joint pain with rashes, prolonged fatigue, dry eyes and mouth, Raynaud phenomenon (fingers turning white in cold), unexplained kidney disease in young women, or features that suggest connective tissue disease. A positive ANA does not diagnose lupus or any specific disease on its own — it simply opens the door to a targeted panel (anti-dsDNA, anti-Smith, anti-Ro/SSA, anti-La/SSB, anti-Scl-70, anti-centromere, anti-RNP).
ABout 5–15% of healthy adults — especially women and older people — have a low-titre positive ANA without any autoimmune disease. This is important for Indian patients to understand: a "weakly positive" ANA from a routine health check is rarely a problem in isolation, but it does need clinical correlation with a rheumatologist before any conclusion. Conversely, a negative ANA makes systemic lupus erythematosus (SLE) very unlikely (>95% of SLE patients are ANA positive).
How to prepare
No fasting required. Take all your medications normally. Mention recent infections (some viral infections cause transient ANA positivity) and any immunosuppressive drugs to your doctor for context.
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 |
|---|---|---|---|
| Anti-Nuclear Antibody (ANA) (U/mL or Ratio)[1][2][3] | Negative: < 20 U/mL (assay-dependent) | Negative ANA makes systemic autoimmune connective tissue disease unlikely, particularly SLE (>95% of SLE patients are ANA positive). It does not rule out organ-specific autoimmune disease (e.g. autoimmune thyroiditis, RA). | Positive ANA suggests autoimmune disease may be present and needs follow-up with specific antibody panel + clinical assessment by a rheumatologist. Higher titres are more clinically significant. A positive ANA is also seen in viral infections, chronic infections, certain drugs (procainamide, hydralazine, isoniazid), and in 5–15% of healthy adults. |
ANA-positive diseases — typical antibody patterns
| Pattern / Antibody | Associated Disease |
|---|---|
| Homogeneous + Anti-dsDNA | SLE (systemic lupus erythematosus) |
| Homogeneous + Anti-histone | Drug-induced lupus |
| Speckled + Anti-Smith | SLE (highly specific) |
| Speckled + Anti-RNP | Mixed connective tissue disease (MCTD) |
| Speckled + Anti-SSA/Ro, Anti-SSB/La | Sjögren syndrome, SLE |
| Nucleolar + Anti-Scl-70 | Diffuse systemic sclerosis |
| Centromere | Limited scleroderma (CREST) |
| Speckled + Anti-Jo-1 | Polymyositis / dermatomyositis |
Frequently asked questions
Does an ANA test require fasting?
No. ANA can be done at any time of day with no special preparation.
My ANA is "weakly positive" — should I worry?
A low-titre positive ANA without any symptoms is common (5–15% of healthy adults). It is usually not significant in isolation. A rheumatologist will look at your symptoms and may order specific antibody tests if needed.
Does positive ANA mean I have lupus?
No. Positive ANA opens the door but does not diagnose lupus. SLE requires a combination of clinical features and specific antibodies (anti-dsDNA, anti-Smith) per ACR/EULAR criteria.
What is the difference between ANA ELISA and ANA IFA?
ELISA is a quick quantitative screen — good for ruling out disease when negative. IFA (indirect immunofluorescence on HEp-2 cells) reports titre and pattern and is the gold standard for confirmation. Many doctors order ELISA first and IFA if positive.
Can ANA become negative again?
Yes, in some situations — drug-induced lupus often resolves when the drug is stopped; transient post-viral ANA fades. In established SLE, ANA typically remains positive lifelong.
Are pregnant women checked for ANA?
Not routinely. ANA is checked in pregnancy if there is a history of lupus, recurrent miscarriage, or new symptoms like rash and joint pain. A positive anti-Ro/SSA antibody in pregnancy can affect the fetal heart and needs specialist input.
How long is the report?
ELISA-based ANA reports typically come back within 24–48 hours. IFA-based ANA takes 48–72 hours because of microscopy slide reading.
Related Autoimmune / Rheumatology tests
Tests commonly ordered alongside ANTI NUCLEAR ANTIBODIES (ANA), or that help interpret an unexpected result.
Sources & references
- NIH MedlinePlus — Antinuclear Antibody (ANA) Test · accessed 2026-05-30T00:00:00.000Z
- ACR — Position Statement on ANA Testing · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Antinuclear Antibody · accessed 2026-05-30T00:00:00.000Z
- EULAR — 2019 SLE Classification Criteria · accessed 2026-05-30T00:00:00.000Z
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