Elm IgE
Measures IgE antibodies to American elm pollen, one of several tree pollens that can cause sneezing, congestion and itchy eyes.
AI-verified against cited sources. Awaiting expert reviewAlso called t8, t008LOINC 6109-3
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What it is
This test measures IgE antibodies to pollen from the American elm (Ulmus americana), also called white elm (ImmunoCAP t8). Elms are wind-pollinated, so their pollen travels easily. Most elms release pollen in late winter or spring, depending on where you live, and some elms in the south flower in late summer or fall. In people who are sensitized, elm pollen can cause hay fever symptoms and can make asthma worse.
Why it matters
A detectable result shows your immune system has made IgE to elm pollen. Whether that causes your symptoms depends on your exposure and on when your symptoms happen. Many people are sensitized to several trees at once, because tree pollens share similar features, so a clinician usually reads this result alongside other tree and pollen tests and the timing of your symptoms.
If it’s high
A level above your lab's range means your body has made more IgE to elm pollen. It shows sensitization, which can happen with or without symptoms. The class number describes how much IgE was found, not how bad your symptoms will be.
Common causes
- Seasonal hay fever (allergic rhinitis) from tree pollen
- Sensitization to elm without any symptoms
- IgE to elm showing up alongside IgE to other trees or pollens that share similar proteins
- A very high total IgE (above about 2,500 kU/L), which can cause a false-positive reading
What can help
- Ask your clinician about ways to lower pollen exposure, such as keeping windows closed on high-pollen days and showering after time outdoors
- Check local pollen reports to see when elm is in season where you live
- Ask whether testing other tree or pollen allergens, or seeing an allergist, would help sort out which pollens matter for you
- Ask your clinician about options for hay fever, including allergy immunotherapy
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: Mayo Clinic Laboratories, ARUP Laboratories, U.S. Food and Drug Administration.
- Adults (this one applies)0–0.09 kU/L
Sources: Mayo Clinic Laboratories, ARUP Laboratories, U.S. Food and Drug Administration
ImmunoCAP IgE classes (Mayo Clinic Laboratories wording)
- Class 0: negativebelow 0.1 kU/L
- Class 0/1: borderline or equivocal0.1 to under 0.35 kU/L
- Class 1: equivocal0.35 to under 0.7 kU/L
- Class 2: positive0.7 to under 3.5 kU/L
- Class 3: positive3.5 to under 17.5 kU/L
- Class 4: strongly positive17.5 to under 50 kU/L
- Class 5: strongly positive50 to under 100 kU/L
- Class 6: strongly positive100 and above kU/L
What can affect your result
- Where you live: elm pollen timing depends on the species and the region
- Overlap with other pollens: tree, weed and grass seasons can overlap, so symptoms may not point to one pollen
- Sensitization to other trees, which often appears alongside elm
- A very high total IgE (above about 2,500 kU/L) can cause false-positive results
- The lab and test brand, because results from different systems are not directly comparable
- A very high total IgE (above about 2,500 kU/L) can cause false-positive results through nonspecific binding (Mayo Clinic Laboratories).
- Different labs and test brands give different numbers for the same blood sample, so compare results from the same lab and system.
- Some labs reject hemolyzed, icteric or lipemic samples (ARUP).
Slow. It usually shifts over months to years, not weeks.
When to talk to a clinician
Talk with a clinician soon if wheezing, chest tightness or shortness of breath come with your pollen symptoms. Call 911 or your local emergency number for severe trouble breathing. For hay fever that stays hard to control, bring this result to your next visit.
Questions you could ask
- How should I read this result together with my other allergy tests?
- Do my symptoms line up with when elm and other trees pollinate where I live?
- Would testing other tree or pollen allergens help?
- What are my options for managing hay fever?
Questions people ask
I tested positive to elm, birch and oak. Am I allergic to all of them?
Not necessarily. Tree pollens share similar proteins, so IgE made against one tree can show up alongside IgE to others. Your clinician looks at which results fit your symptoms, such as when they start in the spring.
When is elm pollen season?
It depends on the elm species and where you live. Most elms release pollen in January or February in the south and as late as April in the north. Some southern elms flower in late summer or fall.
Do I need to stop my allergy medicine before this blood test?
The FDA review of the ImmunoCAP system cites studies showing that commonly prescribed allergy medicines do not interfere with it, unlike skin-prick testing. Ask the clinician who ordered your test before you change any medicine.
Show the science and sources
For clinicians and researchers
Quantitative IgE to an extract of American elm pollen (Ulmus americana, ImmunoCAP t8). Reported as allergen-specific IgE by ImmunoCAP fluoroenzyme immunoassay in kUA/L, with calibrators traceable to the WHO IgE reference (IRP 75/502). The FDA-reviewed system has a limit of quantitation of 0.1 kUA/L and reports up to 100 kUA/L; its maker recommends a 0.35 kUA/L cutoff and tells each lab to set its own range (FDA review K173726). No individual elm pollen allergen has been identified to date (Thermo Fisher encyclopedia), so there is no component test. Elm pollen is speculated to cross-react with related Urticales such as mulberry and nettle, and studies describe cross-reactivity with peach and birch pollen (Thermo Fisher). In one New York City series of 371 allergy patients, 24.6% had elm IgE at class 1 or above, and leaving elm, poplar and beech out of the tree panel would have missed only 1 of 106 patients with any positive tree result, which the authors linked partly to cross-reactive epitopes (Lin 2002). A positive result shows sensitization, not clinical allergy. Nonspecific binding can cause false positives when total IgE exceeds about 2,500 kU/L (Mayo).
LOINC 6109-3 (primary). Specimen: serum.
Sources
- Elm, IgE, Serum (test ID ELM), Mayo Clinic Laboratories
- Allergen, Tree, Elm Tree (ARUP test 0055042), ARUP Laboratories
- Elm, American (T008-IgE Elm, American) (Labcorp test 602476), Labcorp
- ImmunoCAP Specific IgE (allergen component f447) 510(k) decision memorandum K173726, U.S. Food and Drug Administration
- t8 Elm (Allergen Encyclopedia), Thermo Fisher Scientific (Phadia)
- Elm Tree Allergy Facts, Symptoms, and Treatment (Allergy Insider fact sheet), Thermo Fisher Scientific
- Hypersensitivity to common tree pollens in New York City patients, Allergy and Asthma Proceedings (2002)
- Specific IgE antibody criteria for Japanese cedar, Uni-CAP method (Appendix 3, in Japanese), Ministry of the Environment, Japan
- Allergy Testing units (LOINC Community Forum thread), Regenstrief Institute, LOINC Community Forum
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.