Timothy Grass IgE
Measures IgE antibodies to timothy grass pollen, a leading grass allergen and a common cause of summer hay fever and pollen-related asthma symptoms.
AI-verified against cited sources. Awaiting expert reviewAlso called g6, g006LOINC 6265-3
Check your result
Type your result to see where it falls.
Nothing you type here leaves your browser.
What it is
This test measures IgE antibodies to pollen from timothy grass (Phleum pratense), a pasture and hay grass that grows across the United States (ImmunoCAP g6). Grass pollens are among the main causes of seasonal hay fever worldwide. Timothy grass shares many proteins with other grasses, so IgE to it often goes along with IgE to related grasses. Timothy grass grows best in cool, humid, temperate climates, and its pollen counts are highest in early and midsummer.
Why it matters
A result above your lab's range shows your immune system has made IgE to timothy grass pollen. Many people with grass allergy react to several grasses, so a clinician reads this result with the timing of your symptoms. Some labs also offer tests for individual timothy grass proteins (components), which can help show whether your IgE is aimed at grass itself or at proteins found in many pollens.
If it’s high
A level above your lab's range means your body has made more IgE to timothy grass 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) or pollen-related asthma symptoms from grass pollen
- Sensitization to grass pollen without any symptoms
- IgE to timothy showing up alongside IgE to other grasses, such as rye, fescue, orchard grass and Kentucky bluegrass, because grass pollens share similar proteins
- IgE to common plant proteins found in many pollens (such as profilin or polcalcin), which can make several pollen tests positive at once
What can help
- Ask your clinician about ways to lower pollen exposure, such as keeping windows closed on high-pollen days, showering after time outdoors, and wearing a mask when mowing
- Check local pollen reports to see when grass pollen is high where you live
- Ask whether component tests for timothy grass (such as Phl p 1, Phl p 5, Phl p 7 and Phl p 12) or tests for other grasses would help
- 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: ARUP Laboratories, Mayo Clinic Laboratories, U.S. Food and Drug Administration.
- Adults (this one applies)0–0.09 kU/L
Sources: ARUP Laboratories, Mayo Clinic Laboratories, U.S. Food and Drug Administration
ImmunoCAP IgE classes (ARUP Laboratories)
- Class 0: no significant level foundbelow 0.1 kU/L
- Class 0/1: clinical relevance undetermined0.1 to under 0.35 kU/L
- Class 1: low0.35 to under 0.71 kU/L
- Class 2: moderate0.71 to under 3.51 kU/L
- Class 3: high3.51 to under 17.51 kU/L
- Class 4: very high17.51 to under 50.01 kU/L
- Class 5: very high50.01 to under 100.01 kU/L
- Class 6: very high100.01 and above kU/L
What can affect your result
- Where you live: grass species and pollen season differ by climate
- Overlap with other grasses and some cereal crops that share similar proteins
- IgE to profilin or polcalcin, which can make many pollen tests positive together
- Overlap with tree and weed pollen seasons, so symptoms may not point to one pollen
- The lab and test brand, because results from different systems are not directly comparable
- Where a lab draws its cutoff (0.10 or 0.35 kU/L)
- 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 grass pollen season where I live?
- Would component tests or tests for other grasses help?
- What are my options for managing hay fever?
Questions people ask
I tested positive to timothy, rye and Bermuda grass. Am I allergic to all of them?
Not necessarily. Grass pollens share similar proteins, so IgE made against one grass can show up alongside IgE to others. Your clinician looks at which results fit your symptoms, such as when they start in the summer.
What are Phl p 1 and Phl p 5, and why might they be added?
They are the two main timothy grass proteins, and most people with grass pollen allergy have IgE to at least one of them. Tests for them can help show whether your sensitization is to grass itself. Tests for Phl p 7 and Phl p 12 can show IgE to proteins that many pollens share, which can make several pollen tests positive at once.
Do allergy medicines change the result of this blood test?
An FDA review of the ImmunoCAP system cites studies showing that commonly prescribed allergy medicines do not interfere with it. Ask the clinician who ordered your test before you change any medicine.
Show the science and sources
For clinicians and researchers
Quantitative IgE to a Phleum pratense pollen extract (ImmunoCAP g6). ARUP reports it in kU/L with LOINC 6265-3. Reported as allergen-specific IgE by ImmunoCAP fluoroenzyme immunoassay in kUA/L, with calibrators traceable to the WHO IgE reference (IRP 75/502 or the 3rd International Standard 11/234). 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). Timothy is one of the best characterized allergenic grasses, and Thermo Fisher lists the allergens Phl p 1, 2, 4, 5, 6, 7, 11, 12 and 13. Phl p 1 (a beta-expansin) is the key allergen, recognized by IgE in more than 90% of sensitized individuals, followed by Phl p 5 (65 to 90%); about 95% of grass pollen-allergic patients show IgE binding to Phl p 1 and Phl p 5. These two are grass marker allergens. Phl p 12 (profilin) and Phl p 7 (polcalcin) are pollen panallergens, minor allergens that are highly conserved across all pollens (profilins also occur in many plant foods), and IgE to them can make tree, grass and weed pollen tests positive together; polysensitization to tree, grass and weed pollens is found in about 20% of pollen-allergic people and is often based on panallergens (Kleine-Tebbe 2021). ImmunoCAP component codes (Thermo Fisher) are g205 for Phl p 1, g215 for Phl p 5b, g210 for Phl p 7 and g212 for Phl p 12. Cross-reactivity is extensive among Pooideae grasses (perennial rye, June grass, fescue, orchard grass, sweet vernal, redtop) and extends to some corn and maize species. A positive result shows sensitization, not clinical allergy; ARUP notes that results may not correlate with the degree of clinical response or skin testing and that a negative test may not rule out clinical allergy.
LOINC 6265-3 (primary), 112105-2. Specimen: serum.
Sources
- Allergen, Grass, Timothy Grass (ARUP test 0055032), ARUP Laboratories
- g6 Timothy grass (Allergen Encyclopedia), Thermo Fisher Scientific (Phadia)
- Molecular allergy diagnosis using pollen marker allergens and pollen panallergens: Five patterns seen in multiple test reactions to pollen extracts, Allergologie Select (2021)
- ImmunoCAP Specific IgE (allergen component f447) 510(k) decision memorandum K173726, U.S. Food and Drug Administration
- Timothy Grass, IgE, Serum (test ID TIMG), Mayo Clinic Laboratories
- Timothy Grass (test 602506), Labcorp
- Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-Sponsored Expert Panel, Journal of Allergy and Clinical Immunology (2010)
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.