Skip to content
Blood Test Tracker

ANA Titer (IFA)

Shows how strong a positive ANA result is, written as a dilution such as 1:80 or 1:320. A bigger second number means more antibody was present.

AI-verified against cited sources. Awaiting expert reviewAlso called ANA IFA titerLOINC 5048-4

What it is

If the ANA screen is positive, the lab dilutes your blood sample step by step (1:40, 1:80, 1:160 and so on) and finds the largest dilution that still shows glowing antibodies under the microscope. That dilution is the titer. A bigger second number, such as 1:640 compared with 1:80, means there was more antibody. Labs start at different dilutions, usually 1:40 or 1:80. A result of 1:40 can therefore count as positive at one lab and not be reported at another.

Why it matters

Many healthy people have a low ANA titer. In a classic study of healthy adults, about 32 in 100 were positive at 1:40, 13 in 100 at 1:80, 5 in 100 at 1:160 and 3 in 100 at 1:320. In a US government survey, about 14 in 100 people aged 12 and older were positive at 1:80, more often women and older people. Higher titers are more likely to go with an autoimmune condition, and more likely to lead to a specific antibody being found. The titer still has to be read together with the pattern, your symptoms and other tests.

If it’s high

A higher titer means more ANA was found. It is more often seen in autoimmune conditions, but it cannot say which condition, if any, is behind it. Many people with a positive ANA have no autoimmune disease. Your clinician looks at the titer, the pattern, your symptoms and further tests together.

Common causes

  • No autoimmune disease at all: low titers are common, more often in women and in older adults
  • Autoimmune rheumatic conditions such as lupus, Sjögren's syndrome, scleroderma and mixed connective tissue disease
  • Autoimmune liver conditions such as autoimmune hepatitis and primary biliary cholangitis, and autoimmune thyroid disease
  • Some medicines, which can cause a lupus-like reaction
  • A viral infection, usually for a short time

What can help

  • Ask what the titer and pattern mean alongside your symptoms and exam
  • Ask whether more specific antibody tests make sense for you
  • Bring a full list of your medicines and supplements, since some can cause a positive ANA

What can affect your result

  • Screening dilution: labs start at 1:40 or 1:80, and Quest moved from 1:40 to 1:80 in 2026
  • Sex and age: positive results are more common in women and in older people
  • Medicines and recent infections
  • Lab method: slide kit, reading by eye and the lab's own cutoffs
  • The titer comes in steps where each step is twice the last, so small differences between labs are expected
  • Some medicines can cause a positive ANA. Tell your clinician about everything you take, and do not stop any medicine unless your clinician says so (MedlinePlus).
  • A recent viral infection can cause a short-lived positive result (MedlinePlus).
  • Samples that are grossly hemolyzed or lipemic, or contaminated with microbes, may be rejected or may interfere (Quest).
  • Labs start at different dilutions (1:40 or 1:80), read slides by eye and use different slide kits, so titers from different labs are not exactly comparable.

The titer reflects your antibodies on the day of the draw. Whether it changes over time depends on the cause, so your clinician decides if a repeat is useful.

When to talk to a clinician

A titer on its own is not urgent. Ask the clinician who ordered the test to explain it alongside your symptoms. Contact a clinician soon if you have symptoms such as fever, a new rash, or joint pain, stiffness and swelling, and call your local emergency number for chest pain or trouble breathing.

Questions you could ask

  • What dilution does my lab start at, and what pattern was reported with this titer?
  • What does this titer mean in light of my symptoms?
  • Would more specific antibody tests help?
  • Should this be repeated, or is it enough to watch my symptoms?

Questions people ask

Is a titer of 1:80 or 1:160 something to worry about?

Low titers are common in people with no autoimmune disease. In a classic study, about 13 in 100 healthy adults were positive at 1:80 and about 5 in 100 at 1:160. A low-titer result is not a diagnosis. Talk with your clinician about what it means with your symptoms.

Why does my lab start at 1:40 while another starts at 1:80?

Labs choose their own screening dilution. About 60% of labs worldwide use 1:80. Quest moved from 1:40 to 1:80 in 2026 to reduce positive results in people without disease. A 1:40 result is therefore reported as positive at some labs and as negative at others.

Does a higher titer mean my condition is more severe?

A higher titer makes an autoimmune condition more likely, and makes it more likely that a specific antibody will be found. It does not tell you how active or severe a condition is. Your clinician uses your symptoms, exam and other tests for that.

Show the science and sources

For clinicians and researchers

The ANA IFA titer is the reciprocal of the highest serum dilution that still gives positive fluorescence on HEp-2 cells, read in two-fold steps. It is semi-quantitative and depends on the slide, conjugate, microscope and reader. About 60% of labs worldwide screen at 1:80 (cited by Quest), and the 2019 EULAR/ACR SLE classification criteria use ANA at 1:80 or higher on HEp-2 cells as the entry criterion, based on a meta-regression of 13,080 patients in 64 studies that found a sensitivity of 97.8% at that titer (Aringer 2019). Quest states that at 1:40 the sensitivity for SLE is about 98% with a specificity of 67%, while at 1:80 specificity rises to 75% with a fall in sensitivity of less than 1%. In 15 labs testing healthy adults, 31.7% were positive at 1:40, 13.3% at 1:80, 5.0% at 1:160 and 3.3% at 1:320, and the authors recommended reporting at both 1:40 and 1:160 (Tan 1997). In NHANES 1999 to 2004 the prevalence at 1:80 was 13.8% overall, 17.8% in women and 9.6% in men (Satoh 2012). ICAP notes that up to 35% of healthy controls may be positive at 1:40, that the EASI/IUIS recommendation is for each lab to set its screening cutoff at the 95th percentile of healthy controls, and that higher antibody levels are better associated with systemic autoimmune rheumatic disease and with a higher chance of identifying the target antigen on follow-up testing (Damoiseaux 2019). Mayo Clinic Laboratories reports less than 1:80 as negative. Quest reports ANA titer less than 1:80 as negative, 1:80 as a low antibody level and above 1:80 as an elevated antibody level. Mayo reports titer under LOINC 33253-6.

LOINC 5048-4 (primary), 29953-7, 33253-6. Specimen: serum.

Sources

  1. ANA Screen, IFA, with Reflex to Titer and Pattern (test code 249), Quest Diagnostics
  2. Tests for Autoimmune Diseases (ANA), Test FAQ 177, Quest Diagnostics
  3. Antinuclear Antibodies, HEp-2 Substrate, IgG, Serum (test NAIFA), Mayo Clinic Laboratories
  4. Range of antinuclear antibodies in healthy individuals, Arthritis & Rheumatism (1997)
  5. Prevalence and sociodemographic correlates of antinuclear antibodies in the United States, Arthritis & Rheumatism (2012)
  6. 2019 European League Against Rheumatism/American College of Rheumatology Classification Criteria for Systemic Lupus Erythematosus, Arthritis & Rheumatology (2019)
  7. Clinical relevance of HEp-2 indirect immunofluorescent patterns: the International Consensus on ANA patterns (ICAP) perspective, Annals of the Rheumatic Diseases (2019)
  8. ANA (Antinuclear Antibody) Test, MedlinePlus, National Library of Medicine
  9. LOINC codes verified with the NLM Clinical Tables LOINC search (e.g. 5048-4), 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.

Related markers