Diagnostic work-up for food-dependent, exercise-induced anaphylaxis.

Fourteen patients with suspected food-dependent, exercise-induced anaphylaxis (EIAn) were subjected to prick tests with commercial food extracts and common airborne allergens, prick + prick tests with fresh foods, determination of total IgE levels, and specific IgE for 31 foods (CAP System FEIA RAST). All were positive for two or more foods; 10 presented hypersensitivity to 11 or more foods. On the basis of these findings, history data, and responses to food-exercise challenges (treadmill stress tests 90 min after meals containing none of the suspected foods and none associated with skin-test and/or RAST positivity) and suspected food-exercise challenges (SFECs - administered after meals containing the suspected food), three patients were diagnosed as having specific food-dependent EIAn (for wheat in two cases, tomato in one). In nine others, the presence of specific IgE for numerous foods (including those suspected on the basis of histories and utilized in the SFECs) suggests involvement of specific food hypersensitivity, although SFEC confirmation could not be obtained. Avoidance of all foods associated with test positivity 4 h before exercise has prevented all further EIAn episodes in these 12 patients. In two others, the reactions did not appear to be related to IgE directed against specific food allergens, and these subjects have eliminated further reactions by avoiding all meals for the 4 h preceding exercise. These findings emphasize the importance of allergologic testing with a wide panel of food allergens (including foods used for seasoning, such as garlic or parsley) in all patients with suspected food-dependent EIAn. Prick + prick tests with fresh foods and the CAP System RAST disclosed numerous hypersensitivities.