Serum Gliadin Monitoring Extracts Patients with False Negative Results in Challenge Tests for the Diagnosis of Wheat-Dependent Exercise-Induced Anaphylaxis

Background: Challenge testing with wheat plus exercise and or aspirin is a gold standard for the diagnosis of wheat-dependent exercise-induced anaphylaxis (WDEIA); however, the test may often yield false-negative results. Our previous study suggested that an increase in serum wheat gliadin levels is required to induce allergic symptoms in patients with WDEIA. Based on this knowledge, we sought to extract the patients with false negative results in the challenge tests of WDEIA. Methods: Thirty-six patients with suspected WDEIA were enrolled. First, group categorizations―Group I, challenge tests were positive; Group II, challenge tests were negative and serum gliadin were undetectable; Group III, challenge tests were negative and serum gliadin were detectable―were given according to the results of wheat plus exercise and or aspirin challenge testing and serum gliadin levels. Second, diagnoses were made using retests and or dietary management in Group II and III. Results: Positive results for wheat plus exercise and or aspirin challenge tests gave a diagnosis of definite WDEIA in 17 of 36 patients (Group I). Of the remaining 19 challenge negative patients, serum gliadin was undetectable in ten patients (Group II). Of the ten patients (Group II), three of them were diagnosed as definite WDEIA by retesting and six of them were diagnosed as probable WDEIA using a wheat elimination diet, whereas one patient was non-WDEIA. In the rest of the nine challenge negative patients, serum gliadin was detectable (Group III). No allergic episodes with a normal diet provided a diagnosis of non-WDEIA in seven of the nine patients, whereas the remaining two patients were probable WDEIA or had another food allergy because of repeated episodes. Conclusions: Our study revealed that serum gliadin monitoring during challenge testing is useful.