Kentucky Blue Grass (June) IgE
Measures IgE antibodies to Kentucky bluegrass pollen. A higher level means sensitization, which doesn't always cause symptoms.
AI-verified against cited sources. Awaiting expert reviewAlso called g8LOINC 6153-1
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What it is
Kentucky bluegrass (Poa pratensis), also called June grass, is a grass of temperate regions. Its pollen can cause hay fever symptoms in people who are allergic to it. This test measures IgE antibodies in your blood that recognize Kentucky bluegrass allergens. Labs report the result in kU/L, often with a class from 0 to 6.
Why it matters
Grass pollen is a common cause of hay fever, with sneezing, a runny or stuffy nose, and itchy, watery eyes. A result above your lab's cutoff means your immune system has made IgE to Kentucky bluegrass. It can't tell you how strong your symptoms are. Kentucky bluegrass belongs to the same group of grasses as timothy, ryegrass and orchard grass. These grasses share many allergens, so a positive result can reflect the whole group, not just this one grass.
If it’s high
A higher level means sensitization to Kentucky bluegrass pollen. Many people with hay fever in temperate regions have it, and some people have it with no symptoms at all. Labs describe higher classes as a higher chance of a reaction, but the level may not match how strong your symptoms are.
Common causes
- Hay fever (allergic rhinitis) from grass pollen
- Sensitization without any symptoms
- Cross-reactivity with other temperate grasses, such as timothy and ryegrass
What can help
- Take steps to reduce pollen exposure, such as checking local pollen forecasts, keeping windows closed on high-pollen days and showering after time outdoors
- Ask your clinician about ways to manage hay fever, including allergy shots (immunotherapy), which can lower sensitivity to pollen
- Ask whether tests for single grass allergens could help tell related grasses apart
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: Labcorp, ARUP Laboratories, Quest Diagnostics, Thermo Fisher Scientific (Phadia), Journal of Allergy and Clinical Immunology.
- Adults (this one applies)0–0.09 kU/L
Sources: Labcorp, ARUP Laboratories, Quest Diagnostics, Thermo Fisher Scientific (Phadia), Journal of Allergy and Clinical Immunology
ImmunoCAP class scale as printed by ARUP (the manufacturer's revised scale, per UR Medicine Labs 2022)
- Class 0: absent or undetectablebelow 0.1 kU/L
- Class 0/1: clinical relevance undetermined0.1 to under 0.35 kU/L
- Class 1: low level0.35 to under 0.71 kU/L
- Class 2: moderate level0.71 to under 3.51 kU/L
- Class 3: high level3.51 to under 17.51 kU/L
- Class 4: very high level17.51 to under 50.01 kU/L
- Class 5: very high level50.01 to under 100.01 kU/L
- Class 6: very high level100.01 and above kU/L
Labcorp class scale (ImmunoCAP, as printed on Labcorp sample reports dated 2016 to 2019)
- 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 100.01 kU/L
- Class VI: very high100.01 and above kU/L
What can affect your result
- Where you live: Kentucky bluegrass and its relatives grow mainly in temperate regions
- Cross-reactivity with related grasses can make several grass tests positive at once
- Lab and method: class cutoffs differ slightly between labs
- Results from different labs and assay systems can differ, so compare results from the same lab.
- Cross-reactivity with related temperate grasses, such as timothy and ryegrass, can make several grass tests positive at once.
When to talk to a clinician
Call 911 or your local emergency number right away for signs of a severe allergic reaction, such as trouble breathing, swelling of the tongue, lips or throat, dizziness or fainting, a fast heartbeat, or cold, clammy skin that looks pale, gray or bluish. Talk with a clinician if hay fever keeps you from sleeping or doing daily activities, or if you have wheezing, chest tightness or a cough that doesn't go away.
Questions you could ask
- Should we recheck this, and how often?
- Do my symptoms follow the grass pollen season where I live?
- Would tests for single grass allergens help tell related grasses apart?
- What are my options for managing symptoms, including allergy shots?
Questions people ask
I'm allergic to timothy grass. Will Kentucky bluegrass be positive too?
It often is, because these grasses share many allergens. Some experts suggest that allergy shots made from timothy grass can cover this whole group of grasses. Not everyone is sensitized to every grass, though.
Does a positive result mean Kentucky bluegrass causes my symptoms?
Not by itself. The test shows that your body has made IgE to the grass, which is called sensitization. Some people with this IgE have no symptoms. Your clinician looks at the result together with when and where your symptoms happen.
What do the classes 0 to 6 on my report mean?
Labs sort the number into classes from 0 (negative) to 6 (very high). A higher class means more IgE was found. It does not tell you how strong a reaction would be. The cutoffs differ a little between labs. For example, Quest and ARUP start class 1 at 0.35 kU/L, while Labcorp starts it at 0.32 kU/L.
Show the science and sources
Units
- 1 kU/L = 1 kU/L
- 1 kU/L = 1 UA/mL
For clinicians and researchers
Kentucky bluegrass (Poa pratensis) belongs to the Pooideae subfamily of temperate grasses, along with timothy, orchard grass, fescue and ryegrass. A Clinical and Experimental Allergy review describes extensive IgE cross-reactivity within Pooideae (the group 1 allergen Phl p 1 is about 90% identical in sequence to allergens from other Pooideae grasses) and notes it has been suggested that timothy grass allergens are sufficient for allergy shots (subcutaneous immunotherapy) against Pooideae grass allergy. The test is ImmunoCAP g8, measured by fluoroenzyme immunoassay at Labcorp (602496, G008) and ARUP (0055017, June Grass/Kentucky Bluegrass) and reported in kU/L (LOINC 6153-1). Subtropical grasses such as Bermuda and Bahia grass are reported to lack group 5 allergens, and group 1 cross-reactivity between timothy and these grasses is lower. Extract-based tests can't separate true co-sensitization from cross-reactivity; tests for single allergens, such as Phl p 1 and Phl p 5 from timothy grass, are used in specialist care. Class cutoffs differ between labs.
LOINC 6153-1 (primary), 102340-7. Specimen: serum.
Sources
- Kentucky Bluegrass (test 602496), Labcorp
- Sample report for test 602496 (G008-IgE Bluegrass, Kentucky), showing the class table, Labcorp
- Allergen, Grass, June Grass/Kentucky Bluegrass (test 0055017), ARUP Laboratories
- Multiple grass mixes as opposed to single grasses for allergen immunotherapy in allergic rhinitis, Clinical and Experimental Allergy (2013)
- Allergy Blood Test, MedlinePlus (National Library of Medicine)
- Allergic rhinitis (Medical Encyclopedia), MedlinePlus (National Library of Medicine)
- Food Allergy Testing, MedlinePlus (National Library of Medicine)
- VALIDA project: Validation of allergy in vitro diagnostics assays (Tools and recommendations for the assessment of in vitro tests in the diagnosis of allergy), Advances in Laboratory Medicine (2020)
- ImmunoCAP Specific IgE Blood Test: Allergy Test List (interpretation table and test codes), Quest Diagnostics (2017)
- ImmunoCAP Specific IgE blood test results: Interpretation (respiratory results interpretation guide), Thermo Fisher Scientific (Phadia) (2023)
- ImmunoCAP allergy: Change to Reference Interval Interpretation, UR Medicine Labs, University of Rochester Medical Center (2022)
- Prevalence of allergic sensitization in the United States: results from the National Health and Nutrition Examination Survey (NHANES) 2005-2006, Journal of Allergy and Clinical Immunology (2014)
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.