Mountain Cedar (Juniper) IgE
Measures IgE antibodies to mountain cedar pollen, a major winter allergen in parts of the US. A higher level means sensitization, which doesn't always cause symptoms.
AI-verified against cited sources. Awaiting expert reviewAlso called t6LOINC 6178-8
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What it is
Mountain cedar (Juniperus ashei, also called Ashe juniper) is a juniper tree that grows in parts of the south-central United States. It releases pollen in winter, and the allergy it causes is often called cedar fever. This test measures IgE antibodies in your blood that recognize mountain cedar pollen. Labs report the result in kU/L, often with a class from 0 to 6.
Why it matters
Mountain cedar is a major cause of winter hay fever in the south-central US, including Texas. A result above your lab's cutoff means your immune system has made IgE to the pollen. It fits with symptoms such as sneezing, a runny nose and itchy, watery eyes, but it can't tell you how strong your symptoms are. Other junipers and cypresses share allergens with mountain cedar, so a positive result can reflect those trees too.
If it’s high
A higher level means sensitization to mountain cedar pollen. Many people with winter hay fever in the south-central US 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 mountain cedar pollen
- Sensitization without any symptoms
- Cross-reactivity with other junipers and cypresses, and with Japanese cedar
What can help
- Take steps to reduce pollen exposure in the cedar season, such as checking local pollen counts, keeping windows closed on high-pollen days and showering after time outdoors
- Ask your clinician about ways to manage cedar fever, including allergy shots (immunotherapy)
- Ask whether your symptoms line up with the local cedar season
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 and the season: mountain cedar pollen peaks in winter in the south-central US
- Cross-reactivity with other junipers and cypresses can lead to a positive result
- 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 other junipers and cypresses can make a result positive even if you have never been around mountain cedar.
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 winter 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 cedar season where I live?
- Could related trees such as cypress be part of the picture?
- What are my options for managing symptoms, including allergy shots?
Questions people ask
I don't live in Texas. Why is my mountain cedar result positive?
Mountain cedar shares allergens with other junipers and cypresses, so IgE made against those trees can also react with it. Your clinician can look at where your symptoms happen and when.
Does a positive result mean I have cedar fever?
Not by itself. The test shows that your body has made IgE to the pollen, 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
Mountain cedar (Juniperus ashei, synonym J. sabinoides; Cupressaceae) is measured as ImmunoCAP t6 by fluoroenzyme immunoassay at Labcorp (602491, T006) and ARUP (0055007) and reported in kU/L (LOINC 6178-8, named 'Mountain Juniper'). Jun a 1 is the major allergen of Juniperus ashei. A 2022 review of 61 articles found mountain cedar remains a major cause of allergic rhinoconjunctivitis in the south-central US in winter, with avoidance, medicines and subcutaneous immunotherapy as the main strategies. In a 2000 study (skin tests in 10 patients with mountain cedar allergy, plus immunoblots), pollen proteins of 12 Cupressaceae species and of Japanese cedar were extensively cross-reactive, so a positive t6 can reflect sensitization to other Cupressaceae. Class cutoffs differ between labs.
LOINC 6178-8 (primary), 112217-5, 102215-1. Specimen: serum.
Sources
- Cedar, Mountain (test 602491), Labcorp
- Sample report for test 602491 (T006-IgE Cedar, Mountain), showing the class table, Labcorp
- Allergen, Tree, Mountain Cedar (Juniper) Tree (test 0055007), ARUP Laboratories
- Mountain cedar allergy: A review of current available literature, Annals of Allergy, Asthma & Immunology (2022)
- Cross-reactivity among conifer pollens, Annals of Allergy, Asthma & Immunology (2000)
- Development, validation and stability study of an ELISA method to quantify the major allergen Jun a 1 in Juniperus ashei extracts, Journal of Immunological Methods (2026)
- 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.