Pea allergy and peanut allergy
I have a 14 year-old who was allergy tested at 6 months old for eczema and was positive to tree nuts, peanuts, beans, fish, shellfish, eggs, peaches and peas. He strictly avoids all these foods. When he was older, around middle school age, he had a cookie that had oats, raisins, but it had no nuts, and he had coughing, vomiting, and passed out. They checked the ingredients and there were no nuts in it. I tested him and he had a reaction to peanut, 25/45 with pseudopods, with an IgE of 6.19, Ara h 1 0.35 kU/L, Ara h 2 2.89 kU/L, Ara h 3 0.14 kU/L, Ara h 8 <0.10 kU/L, Ara h 9 0.37 kU/L. Green pea showed 3/20, serum IgE 2.08. Multiple skin reactions with corresponding IgE elevations to tree nuts. He has never eaten peas, and he has spit out peas from dishes his mom has made for the rest of the family with no symptoms. Would you challenge him to green peas?
In my approach to food challenges my first question is does the patient / will the patient eat the food in question. If the answer is no then I generally do not proceed with the challenge. The next question that I will have is what is the risk of reaction and am I prepared to treat a severe reaction. If there is anything above a low level risk I generally will defer challenging in my office and work collaboratively with my colleagues at an academic setting to arrange for the patient to be challenged in a location with more advanced care available if needed. I did ask Dr Sicherer for his thoughts: "There is not a test to “differentiate true pea allergy from cross reactivity with peanut”. However, only a small percentage (~5%) of those with peanut allergy react to other beans. When they do, the offenders are more often lupine, chick pea, lentil and green pea (over navy, lima, green bean). It is very common for someone with a positive test to peanut to test positive to other legumes (~50%); clearly most tolerate the food anyway. The scenario here only includes a history of spitting out the peas. I wonder if this is a recent or remote history, since he is 14 years old now. We might be a little suspicious that he “felt something” like a mouth itch and spit it out, but it would be interesting to hear from him or the family more about that. If he already eats other beans (soy, navy, chick pea, etc.) I would count that as indicating less likely pea allergy. If he said he spit it out because it is green and he does not like the look/feel/taste I would be less convinced than if he said it made him itchy. At the end of the day, a food challenge may be needed/warranted but that depends probably on whether the spitting out was recent or remote and if he cares to eat them."
Sicherer SH. Clinical implications of cross-reacting food proteins. J Allergy Clin Immunol 2001;108:881-90.
Dr. Scott Sicherer, FAAAAI
I hope this has been helpful
Dr. Andrew Murphy, FAAAAI