Allergen Component Testing 101

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The most powerful and potentially life-changing diagnostic tool in the food allergy community is also the least known: the allergen component test. We partnered with Allergy Insider, an education platform from Thermo Fisher Scientific who conducts the majority of allergy blood testing in the US and is considered the gold standard, to provide the details you need to know so you can understand if component testing is right for you. Spoiler alert: if you manage allergies to peanut, most tree nuts, milk, egg, or soy, we think the answer is a resounding YES! 

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The Basics | Am I a Candidate For Component Tests | How to Get Tested | Understanding Components | Peanut Component Results | Tree Nut Component Results | Soy Component Results | Milk Component Results | Egg Component Results

The Basics


You are probably familiar with specific IgE (sIgE) tests, the standard blood test that can help you understand if you have a food allergy, which foods you are allergic to, and the likelihood of an allergic reaction (see our guide to IgE Testing).

Less familiar to most people is the allergen component test, which takes a deeper dive into the proteins (components) of each food allergen and can tell you precisely which proteins you are sensitized (allergic) to. Some proteins are associated with a mild reaction or no reaction, while others are associated with anaphylactic reactions. Finding out which protein(s) your body is responding to can alter how you approach your food allergies, including knowing if you may be ready for an oral food challenge. Determining which proteins you are allergic to can be life-changing.


Why are components so important?

When you have a food allergy, your immune system is negatively responding to the protein in the food. The common view is that if you are allergic to, say, peanuts, then that’s the end of the story. However, this approach is not one size fits all, as each food is made of multiple proteins, or components, and each protein (component) is responsible for a different type of allergic reaction, ranging in severity from mild to anaphylactic.


Tell me more.

For example, a peanut has 8 proteins that are clinically relevant, meaning they play a role in food allergies and can be tested for;  milk has 3, and egg has 2. Some food proteins have a very similar biological structure as pollen proteins, similar enough that your body can’t tell them apart. In that scenario, a specific IgE (sIgE) test would show that you have a sensitization (allergy), but an allergen component test can reveal you are allergic to the protein that is unlikely to cause a reaction at all. Of the 8 clinically relevant proteins in peanuts, it has been found that only 5 are likely to result in an anaphylactic reaction, while others would result in mild reactions, or no reaction. In the case of dairy and egg, having an allergy to certain proteins and not others may suggest you will be able to tolerate dairy or egg in baked form.


How does allergen component testing work?

Allergen component testing is a simple blood test that can be done at the same time you get your sIgE test done, or separately, and identifies exactly which proteins within an allergen a person is allergic to and which they are not. 

Why should I get component testing?

Finding out which proteins you’re allergic to can influence how you manage your allergies and determine whether you may be a good candidate for an oral food challenge. Of people who have been diagnosed with a peanut allergy (have a peanut sensitization), 78% are not at risk for a severe allergic reaction. Not everyone is allergic to every protein that is found in a peanut; for example, you can be allergic to one, all, or any amount in between.

Am I a Candidate for Component Tests?


Which allergens are component tests available for?

Within the top 9 allergens, allergen component testing can be done for peanut, certain tree nuts—specifically cashew, walnut, brazil nut and hazelnut; milk, egg, and soy.


Are any other food allergy component tests coming?

Research and testing are ongoing so other tests may become available. Follow @allergyinsider to stay up to date!


Are there allergen component tests for any other allergens?

Scientists at Thermo Fisher Scientific are continually making advancements in allergy testing, so be on the lookout for future food allergen component testing offerings.

Outside of food, component testing is available for some insects, pets, horses, pollens, molds, dust mites and alpha-gal syndrome.

See available tests

How to Get Tested


How do I get an allergen component test?

You can request allergen component testing from your healthcare provider at the same time they order your annual blood testing since the same blood sample can be used for multiple tests. Sometimes, your healthcare provider will have already requested component testing on the lab order without letting you know so you’ll want to ask to make sure or request it if they have not.


How often should I get allergen component testing done?

Any time you get your IgE testing is a good time to also get allergen component testing. Using sIgE and component test results together provides a way to see if patients of any age are outgrowing their allergies. Retesting is also recommended whenever your history or symptoms change.

Spokin tip: Many of us in the Spokin community use component testing to inform for oral food challenges and give us confidence to make those decisions with our healthcare provider. As with sIgE numbers, allergen component test results can change over time. Having the test done on a yearly basis will allow you to track those changes over time and get a clearer picture of the direction in which your results are moving.


Is Allergen Component Testing offered at every lab?

Yes, most labs that offer sIgE testing offer allergen component testing too, including Quest Diagnostics™ and Labcorp. Some small or local labs may not offer it in-house but will typically be able to outsource to another lab. To see if your local lab offers the test, you can use Thermo Fisher Scientific’s Lab Guide and search by your ZIP code for the test called “component test” or “component with reflex”. You can also call ahead to find out if the test is offered. 


Is component testing covered by insurance?

Allergen component testing is widely covered by insurance. You can check with your insurance provider to confirm. Keep in mind that the out of pocket patient responsibility depends on several factors beyond insurance coverage, including the amount of your deductible and if your deductible has been met. If your deductible has been met, then the rate of coverage for testing can range from a portion to 100% coverage.


How established are component tests?

Allergen component testing was first introduced in 2005 with milk and egg. Peanut component tests became widely available in 2011. In 2018, the testing got even better and they were able to test for an additional peanut protein, Ara h 6, which affects 4-5% of the population of people with a peanut allergy.


Can any healthcare provider order component tests?

Any healthcare provider, such as a pediatrician, can order a component test. You can ask for a “component test with reflex”. The component test with reflex is a traditional sIgE test that if positive, indicating you have a sensitization, will automatically conduct the component testing on the same blood sample.

Spokin tip: A “component test with reflex” means that a component test will only be done if your sIgE test comes back positive for an allergen, ensuring you don’t pay for a component test if it isn’t needed.


What if my healthcare provider doesn’t recommend it and I still want it?

You can still advocate for yourself and request to have the test done. If your healthcare provider or specialist is not recommending it you can ask another healthcare provider such as your pediatrician or request one from a virtual platform such as Teladoc Health and ask for a “component test with reflex”. When you are seeking out a healthcare provider, make sure you find one that supports the testing that you and your family are looking for and can help you interpret your results.


Can I get component testing done even if I’m not due for bloodwork?

Yes, you can request to have component testing done independently of your annual blood work and can ask your provider to order it.


How do I know if I have had component testing already?

If you have had a blood test done recently and aren’t sure if they did component testing, you can check your results to see if component result information is available. If you have already had sIgE testing, you can check your healthcare provider’s online patient portal to see your test results. Component detail for peanut, for example, would show results for Ara h 1, 2, 3, 6, 8, 9 and MUXF3 (CCD) and Bet v 2 (Profilin). See the Understanding Components section for detailed component information for additional allergens.

Understanding Components


How do I interpret the results?

Your test results should be interpreted by your healthcare provider. The report you receive will break down your results into the proteins for each allergen you are being component tested for. For example, if you get an allergen component test for peanut, you will receive a result for each of the peanut proteins. Use the chart below to help you interpret what each result means.

The report will provide you with the component letter and number codes, which are the proteins (Ara h 8 as an example of one of the peanut proteins) and associated with that code will be a measurement in kU/L (kilo units of allergen per liter), like you are used to seeing for your specific IgE test.

For example, you might see:

This shows that there is a sensitization to the protein in peanut that is unlikely to cause severe reactions and symptoms may be caused by something else. There is no sensitization to the protein that is associated with severe reactions, which means this person may be able to safely challenge peanut.

Peanut¹


There are 8 clinically relevant proteins in a peanut that component testing analyzes. These proteins can be divided into 3 groups: less likely to cause a reaction, may cause a reaction, and very likely to cause a reaction.

  • MUXF3 (CCD): Sensitization to only this protein may suggest that your symptoms are caused by something other than peanut.
  • Bet v 2 (Profilin): This protein is less likely to cause a severe reaction and is often cross-reactive with pollens that your body mistakes as peanut protein.
  • Ara h 8 (PR-10): This protein is usually associated with mild reactions and oral allergy syndrome but can also be associated with local reactions and is often cross-reactive with pollens that your body mistakes as a peanut protein.
  • Ara h 9 (LTP): Sensitization to this protein could cause a local reaction or a severe reaction.
  • Ara h 1, 2, 3, 6 (Storage proteins): These proteins are associated with increased risk of a severe reaction.

¹ https://www.thermofisher.com/allergy/us/en/living-with-allergies.html?resourceID%3DL2NvbnRlbnQvYWxsZXJneS91cy9lbi9yZXNvdXJjZXMvbGl2aW5nLXdpdGgtYWxsZXJnaWVzL3VuZGVyc3RhbmQteW91ci1wZWFudXQtYWxsZXJneQ%3D%3D&sa=D&source=docs&ust=1659457103379371&usg=AOvVaw10fRd4eBZbo6VGESEkLUO7

Tree Nuts²


Component testing for cashew, walnut, brazil nut, and hazelnut can determine whether you are sensitized (allergic) to the proteins that are associated with a cross-reactivity to other foods and pollens, meaning you are less likely to have a reaction, or whether you are sensitized to the proteins that are associated with having a reaction.

Cashew

  • MUXF3 (CCD): Sensitization to only this protein may suggest that your symptoms are caused by something other than cashew.
  • Bet v 2 (Profilin): Usually associated with mild or localized symptoms; often cross-reactive with pollens, grasses or other fruits that your body mistakes as a cashew protein. May be able to tolerate cooked cashew.
  • Ana o 3 (Storage protein): This protein is associated with increased risk of a severe reaction.

Walnut

  • MUXF3 (CCD): Sensitization to only this protein may suggest that your symptoms are caused by something other than walnut.
  • Bet v 2 (Profilin): Usually associated with mild or localized symptoms; often cross-reactive with pollens, grasses or other fruits that your body mistakes as a walnut protein. May be able to tolerate cooked or roasted walnuts.
  • Bet v 1 (PR-10): These proteins are less usually associated with mild to moderate oral allergy symptoms, but can also include severe reactions. May be cross-reactive with pollens, cooked walnuts may be tolerated.
  • Jug r 3 (LTP): Sensitization to this protein could cause a local reaction or a severe reaction. This protein can also be associated with oral allergy syndrome.
  • Jug r 1 (Storage protein): This protein is associated with increased risk of a severe reaction.

Brazil nut

  • MUXF3 (CCD): Sensitization to only this protein may suggest that your symptoms are caused by something other than Brazil nut.
  • Bet v 2 (Profilin): Usually associated with mild or localized symptoms; often cross-reactive with pollens, grasses or other fruits that your body mistakes as a Brazil nut protein. May be able to tolerate cooked or roasted Brazil nut.
  • Ber e 1 (Storage protein): This protein is associated with increased risk of a severe reaction.

Hazelnut

  • MUXF3 (CCD): Sensitization to only this protein may suggest that your symptoms are caused by something other than hazelnut.
  • Bet v 2 (Profilin): Usually associated with mild, localized symptoms like oral allergy syndrome, is often cross-reactive with pollens that your body mistakes as a hazelnut protein, cooked or roasted hazelnut may be tolerated.
  • Cor a 1 (PR-10): This protein is usually associated with mild reactions and oral allergy syndrome but can also be associated with severe reactions and is often cross-reactive with pollens that your body mistakes as a hazelnut protein. Cooked or roasted hazelnut may be tolerated.
  • Cor a 8 (LTP): Sensitization to this protein could cause a local reaction or a severe reaction. This protein can also be associated with oral allergy syndrome, often cross-reactive with pollens that your body mistakes as a hazelnut protein.
  • Cor a 9, Cor a 14 (Storage proteins): These proteins are associated with increased risk of a severe reaction.

² https://www.thermofisher.com/allergy/us/en/living-with-allergies.html?resourceID=L2NvbnRlbnQvYWxsZXJneS91cy9lbi9yZXNvdXJjZXMvbGl2aW5nLXdpdGgtYWxsZXJnaWVzL3VuZGVyc3RhbmQteW91ci10cmVlLW51dC1hbGxlcmd5

Soy³


Component testing for soy can help you determine if you may be able to tolerate soy in cooked form.

  • MUXF3 (CCD): Sensitization to only this protein may suggest that your symptoms are caused by something other than soy.
  • Gly m 4 (PR-10): This protein can be associated with either mild or severe reactions. Often cooked soy is tolerated.
  • Gly m 5, Gly m 6 (Storage proteins): Associated with severe reactions in both cooked and uncooked forms.

³ https://www.thermofisher.com/allergy/us/en/allergen-fact-sheets.html?cid=0ct_3ac_02082022_F8JCM9&allergen=soy

Milk


Knowing which components of milk someone is allergic to can help determine if that person is likely to tolerate milk in baked form and, if the patient is a child, if they are likely to outgrow their milk allergy.

  • Bos d 4, alpha-lactalbumin: A sensitization to this protein is associated with being able to tolerate milk in baked form (but not in fresh form) and the person is likely to outgrow their milk allergy.
  • Bos d 5, beta-lactoglobulin: A sensitization to this protein is also associated with being able to tolerate milk in baked form (but not in fresh form) and the person is likely to outgrow their milk allergy.
  • Bos d 8, casein: With this protein, a person is at a higher risk of a reaction with all forms of milk and is unlikely to outgrow the allergy.

https://www.thermofisher.com/allergy/us/en/living-with-allergies.html?resourceID%3DL2NvbnRlbnQvYWxsZXJneS91cy9lbi9yZXNvdXJjZXMvbGl2aW5nLXdpdGgtYWxsZXJnaWVzL3VuZGVyc3RhbmQteW91ci1taWxrLWFsbGVyZ3k%3D&sa=D&source=docs&ust=1659457103373371&usg=AOvVaw0OXf59i8ZFaVmtuHr7JhGx

Egg


Understanding which proteins in an egg someone is allergic to will help determine if that person can tolerate egg in baked goods and if they are likely to outgrow the allergy.

  • Gal d 1, Ovomucoid: With this protein sensitization there is a higher risk of a reaction to all forms of egg and the person is unlikely to outgrow their egg allergy.
  • Gal d 2, Ovalbumin: A sensitization to this protein suggests that a person will be able to tolerate egg in baked form and is likely to outgrow their egg allergy.

Spokin tip: Speak with your healthcare provider, but baked generally means baked in something like a cake or muffin at 350°F for 30 minutes. This is because items containing egg need to be baked long enough for all of the allergenic proteins to fully denature so there’s no risk of reaction. If you don’t cook your food long enough, you may react.

https://www.thermofisher.com/allergy/us/en/living-with-allergies.html?resourceID%3DL2NvbnRlbnQvYWxsZXJneS91cy9lbi9yZXNvdXJjZXMvbGl2aW5nLXdpdGgtYWxsZXJnaWVzL3VuZGVyc3RhbmQteW91ci1lZ2ctYWxsZXJneQ%3D%3D&sa=D&source=docs&ust=1659457103376169&usg=AOvVaw20x3OmoKkUq9oU7uJC7ytK


Now you are an expert in this potentially life-changing diagnostic tool and empowered to use component testing to help better manage your food allergies. Speak with your healthcare provider or allergy specialist to add allergen component testing to your next visit. If you would like to find out even more about allergen component testing, please visit our partner, Allergy Insider.


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