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Blood Test Tracker

Birch IgE

Measures IgE antibodies to birch tree pollen to show whether your immune system has become sensitized to it, a common cause of spring hay fever.

AI-verified against cited sources. Awaiting expert reviewAlso called t3, T003LOINC 15283-5

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What it is

This test measures IgE, the antibody type involved in allergic reactions, against pollen from the silver birch tree (ImmunoCAP t3). Birch trees grow in temperate regions and release pollen in spring. Results come in kilounits per liter (kU/L), and many labs also print a class from 0 to 6. Birch pollen shares proteins with other trees, such as alder and hazel, and with some raw fruits, vegetables and nuts.

Why it matters

Birch pollen is a common cause of spring hay fever and can trigger asthma in people who are sensitive to it. Its main allergen, Bet v 1, looks like proteins in foods such as apples, hazelnuts, carrots and celery, so some birch-sensitive people get an itchy mouth after eating those foods raw. This is called pollen-food allergy syndrome, and symptoms are usually limited to the mouth and throat.

If it’s high

A level above the 'none detected' range means the lab found IgE antibodies to birch pollen. This is called sensitization. It is not the same as an allergy, but it can fit with spring hay fever or an itchy mouth after raw fruits or nuts. Higher numbers mean more antibody, not necessarily stronger symptoms. Your clinician can put the result in context.

Common causes

  • Sensitization to birch pollen with no symptoms
  • Spring hay fever or pollen-triggered asthma
  • IgE that cross-reacts with related tree pollens such as alder, hazel or oak
  • Pollen-food allergy syndrome with raw foods such as apple, hazelnut, carrot or celery

What can help

  • Talk with a clinician or an allergist about whether your symptoms follow birch season
  • If foods make your mouth itch, ask whether a Bet v 1 component test or an allergist visit would help, and which raw or cooked foods are likely to bother you
  • Ask about ways to reduce pollen exposure on high-pollen days

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 0–0.09 kU/L. Source: ARUP Laboratories, Labcorp, University of Washington Medicine Laboratory, Children's Minnesota Laboratory, Thermo Fisher Scientific (Phadia), American Academy of Pediatrics (Pediatrics).

ImmunoCAP IgE classes (ARUP, Iowa, Children's Minnesota and CUHK; labs differ on which class an exact edge value falls in)

  • Class 0: no significant level detectedbelow 0.1 kU/L
  • Class 0/1: clinical relevance undetermined0.1 to under 0.35 kU/L
  • Class 1: low0.35 to under 0.7 kU/L
  • Class 2: moderate0.7 to under 3.5 kU/L
  • Class 3: high3.5 to under 17.5 kU/L
  • Class 4: very high17.5 to under 50 kU/L
  • Class 5: very high50 to under 100 kU/L
  • Class 6: very high100 and above kU/L

Labcorp class scale (cutoffs differ from the ImmunoCAP scale above; exactly 100.00 is class V)

  • Class 0: negativebelow 0.1 kU/L
  • Class 0/I: equivocal or low0.1 to under 0.32 kU/L
  • Class I: low0.32 to under 0.56 kU/L
  • Class II: moderate0.56 to under 1.41 kU/L
  • Class III: high1.41 to under 3.91 kU/L
  • Class IV: very high3.91 to under 19.01 kU/L
  • Class V: very high19.01 to under 100 kU/L
  • Class VI: very high100 and above kU/L

What can affect your result

  • Where you live and how much birch pollen you breathe
  • Related tree pollens, which can cause cross-reacting IgE
  • Which raw fruits, vegetables and nuts you eat, if you have pollen-food allergy syndrome
  • The lab and test brand, because results from different systems are not directly comparable
  • Antihistamines generally don't interfere with blood IgE tests, unlike skin tests (AAP). MedlinePlus advises telling your provider about everything you take, since some medicines may matter for this test, so ask your clinician before changing any medicine.
  • Assays from different manufacturers aren't equivalent, so compare results only from the same lab and method (AAP).

Slow. IgE levels usually shift over months to years, not weeks.

When to talk to a clinician

Get urgent medical help for trouble breathing, throat tightness, widespread hives, repeated vomiting, dizziness or fainting after eating a food. Otherwise, talk with a clinician if hay fever is hard to control, if you wheeze or feel chest tightness in tree season, or if foods cause more than mild mouth itching.

Questions you could ask

  • Which lab method was used, and should I use the same lab for future results?
  • Do my symptoms line up with birch pollen season?
  • Would a birch component test, such as Bet v 1, add useful information?
  • Which foods might bother me, and what signs mean I should get urgent help?
  • My result is in the usual range but I still have symptoms in spring. What else could be causing them?

Questions people ask

Why does my mouth itch after raw apples if I react to birch?

Proteins in birch pollen look a lot like proteins in some raw fruits, vegetables and nuts, so the same antibodies can react to both. Symptoms are usually limited to the mouth and throat and are more likely with raw foods, and cooking often lessens the reaction. Your clinician can tell you which foods may be a problem for you.

Does a high birch result mean my symptoms will be bad?

Not necessarily. Higher levels mean more antibody and a higher chance of symptoms, but the number does not predict how strong a reaction will be. Your history matters as much as the result.

What do the class numbers 0 to 6 mean?

The class groups the kU/L number from none detected (class 0) to very high (class 6). Higher classes mean more antibody and a higher chance of a reaction, but not a more severe one. Labcorp's class cutoffs differ from the ones ARUP and many hospital labs use, so compare the kU/L number rather than the class between labs.

Show the science and sources

For clinicians and researchers

Quantitative IgE to a silver birch (Betula verrucosa) pollen extract (ImmunoCAP t3) by fluoroenzyme immunoassay; ARUP and Labcorp both use the ImmunoCAP system, which reports about 0.1 to 100 kUA/L. Results from the different FDA-cleared IgE systems are not equivalent (AAP 2012). Bet v 1 (t215), a PR-10 protein, is the major allergen and the marker of genuine birch sensitization, and Bet v 1-like proteins in foods (Mal d 1 in apple, Cor a 1 in hazelnut, Ara h 8 in peanut, Gly m 4 in soy, Api g 1 in celery, Dau c 1 in carrot) drive pollen-food allergy syndrome (Thermo Fisher). Bet v 2 (profilin, t216), Bet v 4 (polcalcin) and Bet v 6 are minor, cross-reactive allergens; sensitization to those alone points to a different primary allergen source and makes birch immunotherapy less suitable. A positive t3 with negative components can mean sensitization to an untested allergen. The AAP report lists birch pollen cross-reactivity with hazelnut, peanut and soy as a cause of positive food tests without clinical allergy. ARUP reports 0.10 to 0.34 kU/L as 'clinical relevance undetermined', and UW Medicine lists 0.00 to 0.34 kU/L (effective 2016).

LOINC 15283-5 (primary), 112146-6. Specimen: serum.

Sources

  1. Allergen, Tree, Birch Tree IgE (test 0055058), ARUP Laboratories
  2. Common Silver Birch (test 602936), Labcorp
  3. Birch, IgE Result (EBIRC1), University of Washington Medicine Laboratory
  4. Sample report 607120, Allergens with Component Reflexes Area 20 (class description table), Labcorp
  5. Allergen (IgE) ImmunoCAP, University of Iowa Hospitals & Clinics, Pathology Handbook
  6. Allergen IgE (laboratory test information), Children's Minnesota Laboratory
  7. Immunoglobulin E (IgE, Allergen-Specific), Serum, Chinese University of Hong Kong, Prince of Wales Hospital ward manual
  8. Your quick guide to using ImmunoCAP Specific IgE testing, Thermo Fisher Scientific (Phadia) (2024)
  9. Allergy Testing in Childhood: Using Allergen-Specific IgE Tests (clinical report), American Academy of Pediatrics (Pediatrics) (2012)
  10. Allergy Blood Tests, MedlinePlus (National Library of Medicine)
  11. ImmunoCAP Specific IgE tests: Birch pollinosis (testing algorithm), Thermo Fisher Scientific (Phadia) (2026)
  12. Allergen Encyclopedia: Birch (t3), Thermo Fisher Scientific (Phadia)
  13. Pollen-Food Allergy Syndrome in Children: Global Prevalence and Pathogenesis, Nutrients (2026)

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

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