CRD Testing

CRD Testing

Component Resolved Diagnostic Testing (known as CRD) is a new type of food allergy testing not yet approved by the FDA in the United States. The test is being used in Europe with great and interesting results.

The basic idea behind CRD is that foods often have more than one protein that individuals can be allergic to. For instance; Ara h1, h2 and h3 are peanut proteins most correlated to severe allergic reactions in individuals with a peanut allergy. However, there are other peanut proteins that will give a positive peanut allergy result on standard tests that in fact cause only mild reactions. These current tests check for peanut protein period and not for the individual proteins.

This could explain why recent studies have shown that not everyone who thinks they have a peanut allergy are truly allergic or severely allergic. This isn’t to diminish the fact that there are many individuals that are in fact severely allergic to peanuts or other foods. However, testing advancements like this one can help to potentially differentiate those who are likely to suffer severe reactions from those who may only have mild reactions.

We recently requested (and underwent) CRD testing from our personal allergist. Our son was tested and diagnosed with severe (life threatening) peanut allergies around the age of 2, after a walnut reaction. Like many, the then allergist tested for a variety of foods we had never had reactions to. We’ve avoided peanuts faithfully for 5+ years now and have in fact altered our lives significantly to keep our son safe.

Peanut products are not allowed in our home. We avoid any foods with warning labels like “may contains peanuts”. We rarely attend large sporting events (like Red Sox games) unless there is a peanut safe section. We only fly peanut safe airlines and have boycotted South West after an in flight reaction to something our son touched on the airplane floor.

We started to wonder. Had we ever really SEEN a severe allergic reaction to peanuts? There were mysterious hives on occasion where we suspected peanut, but we were never 100% sure. Were we avoiding peanuts and altering our lives unnecessarily? This new testing could take us one step closer in finding out.

After our allergist did his own research, he agreed to go ahead with the testing and we were the first in his office to do so. He was kind enough to call us “pioneers” which is flattering but “mom” is really the only word that comes to my mind.

We were doing traditional testing anyway, so the CRD test for peanut only involved an additional blood draw and a $200. payment on my end. The testing is not FDA approved in the US and is not covered by insurance.

The results came in and our fantastic and very supportive allergist called us with the news. As we suspected, our son is allergic to ALL of the peanut proteins tested and will more than likely suffer a severe reaction if peanuts are ever ingested. We suspected this much as his standard peanut skin prick tests were significantly positive and his peanut RAST score has always been in the 70’s-90’s.

Why did we go ahead with the additional test and would we do it again?
Honestly, I would do it again in a heartbeat. The goal for us was to get one step closer in seeing how allergic to peanuts our son really is. We don’t have to currently change our way of life or how we manage from what we were doing before. However, if the test showed that our son was not allergic to the more severe peanut proteins then we might have considered a hospital setting food challenge due to the abscense of any definite peanut allergy reaction. We also might have backed off on our strict avoidance policy of foods with peanut warning labels.

Knowing that our son is “definitely”, and potentially severely, allergic to peanuts gives us peace of mind in knowing that we are currently (and have been) doing the right thing to keep him safe.

For more information on CRD testing click on Phadia Food Allergy Testing.


  • comment-avatar
    Jim Thompson MD 6 years

    You may want to have your allergist to run the ISAC component panel, it is not much more $$ than the component peanut panel. It includes the peanut components but also includes 103 of the most relevant protein components from foods, pollens, danders, dust mite… It gives a more complete allergy profile.

    You may also wish to ask your allergist to determin the IgG4 levels. IgE to Ara h 2 with a low level of IgG4 represents a risk for reaction to small amounts of peanut. If the IgG4 is elevated there is at least some tolerance to peanut.

  • comment-avatar

    Thank you Jim for the information and for your comment.
    We went with the CRD to determine my son’s peanut allergy levels. We have an idea of where he is at with his other allergens but were questions his high numbers with peanut.

    Turns out he is allergic to ALL peanut proteins including Ara h1 and on. We are looking into enrolling in an immunotherapy or other peanut allergy study when the time is right.

  • comment-avatar
    David Kittle 6 years

    Ruth, thanks so much for sharing your experience! My wife and I had heard of newer, more advanced testing methods but have found our son’s current physician(s)s/allergist(s) inexplicably resistent to these new testing measures. Our son has never had a reaction directly related to peanuts. He was diagnosed through traditional blood and scratch tests after he had gotten peanut butter on his face and it caused some mild redness (much in the same way as my duaghter would get when getting birthday cake frosting on her face). Out of an abundance of caution (since it was peanuts we were dealing with) we decided on the allergy testing. And the rest as you say is history…over eight years of extreme diligience and life altering changes. Like you, we would do it again without question. My wife and I are hoping that you could share your physicians name via email so that we may contact him/her in hopes of getting this testing done for our son. We live in Colorado but are willing to roadtrip to just about anywhere (we actually quite enjoy it – one of those changes!). Thanks again for sharing…it gives us hope…and could, like you, just give us clarity as well…thanks!

  • comment-avatar

    David – I’m in MA but am happy to share information with you. Feel free to email me your email address – you can contact me via the contact button at the bottom of every page.

  • comment-avatar
    Ileana Jacolow 5 years

    Hi Ruth,
    I just wanted to also say Thank You for sharing this story. Our seven year old was diagnosed with a peanut allergy when he was two although he has never had a reaction. A friend of mine showed an article to me on the CRD test and then I did research and read about your experience. My pediatrician (who’s son also has a peanut allergy) was resistant, and our regular allergist who we use had not performed the test either but was willing to do it. I was lucky enough though, to run one other google search and found someone in Manhattan where we live who performs this test regularly and we were able to get our son in for an appointment relatively quickly.

    We just got the results back and he is a true positive. We have to go back to meet with the Dr to get more details but now I know that we have to continue to be vigilant in our avoidance of peanuts.

    The reason we did it is because it was becoming a problem for our son and he was becoming a little phobic. I hear that can happen as they get older (he’s in 2nd grade) and I wanted to help him to manage the allergy and to find out the severity. Of course I was hoping that he wasn’t actually positive and therefore didn’t have to live in fear of a reaction but it’s better that we know even if it’s not what I hoped to hear.

    I too would do the test again in a heartbeat because I feel it’s always best to be armed with as much information as possible.

    So thank you for educating us and sharing your story.
    If anyone needs an allergist in NYC area, I will be happy to share the details.

  • comment-avatar

    Ileana – thank you so much for commenting and sharing your experience. I’m glad you found the post helpful and sorry to hear you didn’t get the results you wanted. My son is 8 and also in 2nd grade. They are at an age where a lot is happening with them psychologically. They are just starting to “really” notice they are different and can’t take part in some things that other people can. Because of this we are personally trying to get into a peanut allergy trial/study with the hope of desensitizing our son to peanuts. Perhaps that’s an alternative for you if you would or your son would be interested.

  • comment-avatar
    Suzanna Paxton 5 years

    hi Ruth,
    thank you for telling your story.
    Both of my children are anaphylactic – my son to egg and daughter to peanut, tree nuts & sesame seed.
    Do you or your allergist know anyone in Australia that does this test? and,
    does this test cover proteins associated with food other than peanuts?
    Many Thanks Suzanna

  • comment-avatar

    Suzanna – I do not know of an allergist in Australia – however you can contact the Australasian Society of Clinical Immunology at to see you can find someone in your area.

    The CRD test is not just for peanuts. It can also be used to break down proteins in other common allergens.

    You might also want to contact Phadia – and see if they sell their tests in Australia. If they do – they should be able to give you a name of an allergist.

    Best of luck!

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