Thank you for your inquiry.
There are several key points missing from your history that would help you interpret negative tests. These are:
1. First of all, is this child atopic? Does she have allergic rhinitis, asthma, or atopic dermatitis?
2. Secondly, does she have trouble with all fish and all preparations of fish? That is, is she intolerant to salmon, sea bass, et cetera?
3. Thirdly, is she intolerant of fish regardless of how it is prepared (for example, salmon in the form of gravlax, fried catfish, baked fish?
Of course, if she is highly atopic, you would be more reluctant to allow the child to go without an epinephrine injector. If she reacted to all fish, this would be somewhat unusual and might imply an intolerance. In addition, if she could tolerate one preparation of the same fish better than another, it would also point toward an intolerance.
Having said this, the first step is to proceed as you have done, and that is rule out an IgE-mediated mechanism as best you can by testing. You have done due diligence in this regard with one or possibly two additional steps that should be added to your workup.
The first of these would be to do a prick-to-prick test employing a fish that she does not tolerate, cooked in a fashion that she has had trouble eating in the past. If this test is negative, you have done all you can do besides an oral challenge to rule out an IgE-mediated mechanism. I would feel reasonably comfortable that this was an intolerance if all of these tests were negative, but if you still feel uncomfortable about her going without an epinephrine injection, then I would perform an oral challenge in the office while you evaluate her to make sure there is no other manifestation such as flushing, pruritus, et cetera.
If the challenge was negative for any other manifestation, and all of the above noted tests have been performed, then you have done as much as you can do in this situation to rule out an IgE-mediated mechanism, and therefore it would simply be a matter of your own judgment as to whether you should further try and talk the mother into keeping an automatic epinephrine injector with her. However, in my view, I would think that the child’s reaction, under these circumstances, was an intolerance rather than an IgE-mediated event and would therefore think it reasonably safe for her to go without an injector. Nonetheless, the final decision would be one based upon your own clinical judgment and discussions with the mother.
Thank you again for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.