Quick Facts
- Sample: Blood
- Fasting: No special preparation required
- Turnaround: 3-5 business days. May take longer based on weather, holiday, or lab delays.
What This Test Measures
This test measures the level of walnut-specific IgE antibodies in your blood (biomarker F256-IgE Walnut). When your immune system identifies walnut proteins as a threat, it produces IgE antibodies specific to those proteins, and this test quantifies that antibody response using a blood sample. It measures IgE reactivity to walnut only and does not test for other tree nuts, foods, or antibody classes such as IgG.
Benefits
- Measures walnut-specific IgE with a single blood draw
- No special preparation or fasting required
- Results delivered online within days
- Focused, single-allergen result for walnut IgE
- Can support a conversation with your healthcare provider about walnut reactions
Who Is This Test For?
- Individuals who have experienced symptoms after eating walnuts or walnut-containing foods
- People working with a healthcare provider to evaluate a possible walnut allergy
- Individuals wanting a walnut-specific IgE result to discuss with a healthcare provider
- People who prefer blood testing over other allergy testing methods
- Individuals monitoring walnut-specific IgE levels over time under provider guidance
How It Works
- Order Your Test Online
- Visit a Local Lab
- Get Results Online
FAQ
1. What does this test measure, and how is it different from other food allergy tests?
This test quantifies walnut-specific IgE antibodies in a blood sample rather than testing multiple foods at once. Because it targets a single allergen, it differs from broader panels that screen for several foods or antibody classes, such as IgG, at the same time. The result reflects walnut IgE only and does not indicate anything about other tree nuts or foods.
2. Who should consider this test, and when?
Anyone who has noticed symptoms after eating walnuts, or who wants a walnut-specific IgE result to bring into a conversation with a healthcare provider, may find this test relevant. It can also be useful for people already working with a provider to evaluate a suspected walnut allergy. This test is not intended as a general food allergy screening.
3. Do I need to fast or prepare for this test?
No special preparation is required for this test. You can visit the lab and provide your blood sample without fasting or adjusting your diet beforehand.
4. How long will it take to get my results?
Results are typically available in 3 to 5 days, though this may take longer depending on weather, holidays, or other lab delays. You'll be able to view your results online once they're ready.
5. How should I interpret my results, and what if they are abnormal?
Your result reflects the level of walnut-specific IgE detected in your blood, but interpretation depends on your symptom history, prior reactions, and other clinical factors that only a healthcare provider can evaluate together with this result. A detectable level does not by itself confirm a clinical walnut allergy, and a low or undetectable level does not guarantee that walnuts can be consumed without risk. If your results fall outside the expected range, review them with a qualified healthcare provider, who can help determine whether additional evaluation is appropriate. This test does not diagnose an allergy, predict reaction severity, or indicate whether walnuts are safe for you to eat.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
No special preparation is required for this test.
Cross-Reactivity
Cross-reactivity can occur when your immune system recognizes proteins in one food as similar to proteins in another food or substance, sometimes triggering a reaction to both. This test measures walnut-specific IgE only, and it does not test for any of the other foods or substances described below. The examples below are not exhaustive and are meant to provide general educational context, not a confirmed list of additional allergies. Having a walnut allergy does not mean you will necessarily react to any of these other items, and this section is not a recommendation that you need additional testing.
Pecan: Walnut and pecan share closely related proteins, and research has found this to be one of the most strongly linked cross-reactive pairs among tree nuts.
Other tree nuts: Some studies suggest that having an allergy to one tree nut can be associated with sensitization to other tree nuts, though the strength of this relationship varies by nut.
Birch pollen: Some individuals with tree nut allergies also react to birch pollen due to shared protein structures, a pattern sometimes described as oral allergy syndrome or pollen food allergy syndrome.
Depending on your symptoms, reaction history, or other allergies, discussing related allergen testing with your healthcare provider may help clarify whether further evaluation could be useful.
