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Blood Test Tracker

ENA Screen (extractable nuclear antigens)

Looks for antibodies to several proteins inside the cell nucleus at once; a positive screen is followed by tests that name the exact antibody.

AI-verified against cited sources. Awaiting expert reviewAlso called ENA, Anti-ENALOINC 14722-3

What it is

Your immune system can make antibodies against proteins inside the nucleus of your own cells. The extractable nuclear antigens (ENA) are a group of these proteins. An ENA screen looks for antibodies to several of them in one test. Each lab chooses its own list. Common ones are Sm, RNP, SSA (Ro), SSB (La), Scl-70 and Jo-1, and some labs add others such as centromere. The result is usually printed as negative or positive.

Why it matters

A positive screen can be an early clue that the immune system is reacting to the body's own tissue. These antibodies are seen in conditions such as lupus, Sjögren's disease, scleroderma, mixed connective tissue disease and some muscle diseases. The screen does not say which antibody is present or whether any condition is behind it. Your clinician will usually order tests for each antibody next and read them together with your symptoms and exam. A negative screen makes these conditions less likely but does not rule them out.

If it’s high

A positive result means the screen found antibodies to at least one of these nuclear proteins. This is a clue, not a diagnosis. Similar antibodies are found in some people who have no autoimmune disease, and they can follow some infections and medicines. Your clinician will put the result in context, usually after tests that name the specific antibody.

Common causes

  • Antibodies in a person with no autoimmune disease (antinuclear antibodies as a group are found in some healthy people, more often with age)
  • An infection or a medicine that triggers antinuclear antibodies
  • Lupus (systemic lupus erythematosus)
  • Sjögren's disease, which causes dry eyes and dry mouth
  • Systemic sclerosis (scleroderma)
  • Mixed connective tissue disease
  • Inflammatory muscle disease (myositis), including antisynthetase syndrome, which is linked to Jo-1 antibodies

What can help

  • Ask which individual antibodies were found, or whether follow-up tests were run
  • Write down symptoms such as joint pain or swelling, rashes, dry eyes or mouth, fingers that change color in the cold, or muscle weakness, and share them with your clinician
  • Share a full list of your medicines and supplements with your clinician
  • Ask whether a visit with a rheumatologist (a specialist in autoimmune conditions) would help

What can affect your result

  • Lab method and antibody list: immunodiffusion, ELISA, bead and line assays do not always agree
  • Sex: some antibodies, such as anti-SSA, are found more often in women (9% of women and 2% of men in one hospital study)
  • Age: antinuclear antibodies become more common with age
  • Medicines and infections can trigger antinuclear antibodies
  • Starting or stopping treatment for an autoimmune condition can change results
  • Labs use different methods and different lists of antibodies (for example immunodiffusion, ELISA, multiplex bead or line immunoassay), so a screen that is positive at one lab can be negative at another.
  • Antinuclear antibodies as a group can be triggered by some medicines and by some infections, so a positive result does not always point to an autoimmune condition.
  • Starting or stopping treatment for an autoimmune condition can change which antibodies are found.
  • Labs may reject bacterially contaminated or very fatty (lipemic) samples. ARUP does this for its ENA test.

Results usually stay the same from one test to the next. In a large study of people tested more than once (a median of about a year apart), 86% had no change in their ENA results.

When to talk to a clinician

See your clinician soon if a positive result comes with new or worsening symptoms such as joint swelling, a rash, dry eyes or mouth, fingers that turn white or blue in the cold, muscle weakness or an unexplained fever. Call 911 or your local emergency number for chest pain, severe trouble breathing or confusion.

Questions you could ask

  • If my screen is negative but my symptoms continue, what should we check next?
  • Which antibodies does my lab include in its ENA screen?
  • Which specific antibodies were found, and what do they usually go with?
  • Do my symptoms and other results fit with this, or could something else explain it?
  • Should I see a rheumatologist, and what should I watch for in the meantime?

Questions people ask

My ANA was negative. Can my ENA screen still be positive?

Yes. In a review of 28 studies, 1.4% of ANA-negative samples had a positive ENA when no reason for testing was given. The figure was 8.1% when a connective tissue disease was suspected and 44.1% in people already diagnosed. In the review, anti-SSA/Ro antibodies and anti-tRNA synthetase antibodies (such as Jo-1) were linked to this pattern.

Does a positive ENA screen mean I have lupus?

No. A positive screen only says that at least one of these antibodies was found. Several conditions can cause them, and similar antibodies are also found in some people who have no autoimmune disease. Your clinician will use the follow-up tests, your symptoms and your exam to decide what the result means.

Will I need to repeat the ENA test?

Usually not. In a large study, most repeat tests gave the same answer, and a new positive after a negative result was uncommon. The authors of that study suggest repeating it only if your symptoms change.

Show the science and sources

For clinicians and researchers

An ENA screen detects IgG antibodies to a mix of soluble nuclear and cytoplasmic proteins, commonly Sm, U1-RNP, SSA/Ro, SSB/La, Scl-70 and Jo-1. Some kits add Ro52, centromere B, ribosomal P, histones or chromatin. Methods include double immunodiffusion, ELISA, fluorescent enzyme immunoassay, multiplex bead assays and dot or line immunoblots. The screen is qualitative with a lab-specific threshold. One published algorithm treated a ratio of 0.7 or higher on a connective tissue disease screen as borderline or positive and then confirmed with single-antigen assays. A hospital laboratory's FEIA ENA screen uses the same 0.7 point: under 0.7 is negative, 0.7 to 1.0 equivocal and above 1.0 positive. Algorithms differ: some labs run ENA only after a positive HEp-2 ANA, others run it up front or on request, for example when anti-SSA is suspected, because HEp-2 immunofluorescence can miss anti-SSA. A 2026 meta-analysis of 28 studies (28,552 ANA-negative samples) found ENA positivity of 1.4% when no indication was stated, 8.1% when connective tissue disease was suspected and 44.1% in confirmed disease, with anti-SSA/Ro and anti-tRNA synthetase antibodies as significant drivers. So a negative ANA does not exclude a positive ENA. In a three-centre cohort of 28,557 requests, SSA60 and Ro52 were each about 31% of positive specificities, followed by CENP-B (14.5%), SSB (10.2%), RNP (6.1%), Scl-70 (3.7%) and Sm (3.5%). Repeat ENA testing did not change in 86.1% of patients, and only 1.8% turned positive after an initial negative.

LOINC 14722-3 (primary), 63391-7, 30342-0. Specimen: serum.

Sources

  1. An international multicenter retrospective analysis of repeated anti-ENA testing in ANA-associated rheumatic diseases, a data-driven proposal to increase testing efficacy, Journal of Translational Autoimmunity 2025;11:100298 (2025)
  2. Frequency of extractable nuclear antigen seropositivity among individuals seronegative for antinuclear antibodies on indirect immunofluorescence: a systematic review and meta-analysis, Frontiers in Immunology 2026;17:1745828 (2026)
  3. Assessment of the Impact of Anti-nuclear Antibody (ANA) Titer and Pattern on Anti-extractable Nuclear Antigen (ENA) Positivity: Experience at Cheikh Khalifa Hospital, Cureus 2025;17:e85723 (2025)
  4. ANA (Antinuclear Antibody) Test, MedlinePlus (U.S. National Library of Medicine)
  5. Antinuclear Antibodies (ANA), IgG by ELISA with Reflex to ANA HEp-2 Substrate, IgG by IFA and ENA Confirmation (ARUP test 0050317), ARUP Laboratories (2026)
  6. Extractable Nuclear Antigen Antibodies (Smith/RNP, Smith, SSA 52, SSA 60, and SSB) (ARUP test 0050652), ARUP Laboratories (2026)
  7. ENA Screen (Symphony IgG) - No Reflex (Bassett Healthcare laboratory test LAB3191), Bassett Healthcare Network Laboratory
  8. LOINC codes verified with the NLM Clinical Tables LOINC search (e.g. 14722-3), U.S. National Library of Medicine

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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