Thank you for your inquiry.
I am referring your question to Dr. David Fleischer, who is a nationally known expert in food allergy, and who regularly performs food challenges in children.
As soon as we hear from Dr. Fleischer, we will forward his response to you.
Thank you again for your inquiry.
Phil Lieberman, M.D.
We received a response from Dr. David Fleischer regarding your inquiry. Thank you again for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.
Response from Dr. David Fleischer:
The patient has multiple food allergies and a peanut IgE level of 45. He ate 1/4 of a large Reese's PNB cup. 2 large Reese's PNB cups contain only 5 gm of protein (Hershey's website), so at most he ate approximately let's say 0.6-7 gm of peanut since one PNB cup is only 2.5 gm of protein - some of that protein is also from dairy. Therefore, the fact is that he likely just did not reach his threshold to react.
I start most of my peanut challenges at 0.5 gm of peanut butter - the exposure this patient had.
I personally would not challenge this patient with such a high IgE level and large skin test, as there is essentially no chance of him passing a FULL challenge of peanut butter (2 tablespoons or 35 grams). I only challenge patients when their IgE level to peanut is less than 2 kU/L.
You could do a fresh skin test to peanut butter to confirm the sensitivity, and you could do peanut component testing in this patient. I would guess that Ara h 1,2, and 3 would come back positive in this subject. I would only challenge this subject if he had negative Ara h 1, 2 and 3 and ONLY positive Ara h 8, which I highly doubt to be the case.
As far as giving this patient small doses of peanut butter daily, I would NOT recommend this. This is then treating the patient with oral immunotherapy, which is not recommended or FDA approved yet. Unless you have a clinical trial to do so, I would not do this. The 8% mentioned is from a study that looked at recurrent peanut allergy: if a patient outgrows their peanut allergy, then if they do not eat it regularly in their diet after passing a food challenge, then they have an 8% chance of it recurring (not 8% chance of a systemic reaction).
I would not state this patient as having a successful ingestion of peanut as he only consumed less than 1 gm of peanut, far below a full food challenge dose to say he is not allergic to peanut. I would say he has been allergic to peanut all along.
David M. Fleischer, M.D.
Associate Professor of Pediatrics
Division of Pediatric Allergy and Immunology National Jewish Health