Diagnosis of exercise-induced anaphylaxis: current insights

Exercise-induced anaphylaxis (EIAn) is defined as the occurrence of anaphylactic symptoms (skin, respiratory, gastrointestinal, and cardiovascular symptoms) after physical activity. In about a third of cases, cofactors, such as food intake, temperature (warm or cold), and drugs (especially nonsteroidal anti-inflammatory drugs) can be identified. When the associated cofactor is food ingestion, the correct diagnosis is food-dependent EIAn (FDEIAn). The literature describes numerous reports of FDEIAn after intake of very different foods, from vegetables and nuts to meats and seafood. One of the best-characterized types of FDEIAn is that due to ω5-gliadin of wheat, though cases of FDEIAn after wheat ingestion by sensitization to wheat lipid transfer protien (LTP) are described. Some pathophysiological mechanisms underlying EIAn have been hypothesized, such as increase/alteration in gastrointestinal permeability, alteration of tissue transglutaminase promoting IgE cross-linking, enhanced expression of cytokines, redistribution of blood during physical exercise leading to altered mast-cell degranulation, and also changes in the acid-base balance. Nevertheless, until now, none of these hypotheses has been validated. The diagnosis of EIAn and FDEIAn is achieved by means of a challenge, with physical exercise alone for EIAn, and with the assumption of the suspected food followed by physical exercise for FDEIAn; in cases of doubtful results, a double-blind placebo-controlled combined food-exercise challenge should be performed. The prevention of this particular kind of anaphylaxis is the avoidance of the specific trigger, ie, physical exercise for EIAn, the assumption of the culprit food before exercise for FDEIAn, and in general the avoidance of the recognized cofactors. Patients must be supplied with an epinephrine autoinjector, as epinephrine has been clearly recognized as the first-line intervention for anaphylaxis.