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.