title: The necessity for dual food intake to provoke food-dependent exercise-induced anaphylaxis (FEIAn): a case report of FEIAn with simultaneous intake of wheat and umeboshi.
abstract: BACKGROUND
  Food-dependent exercised-induced anaphylaxis (FEIAn) is classified among the physical allergies. Many different food allergens have been reported, but the pathophysiology of FEIAn remains unknown. Furthermore, provocation tests with a suspected food do not always succeed in patients with FEIAn.
  
  
  OBJECTIVE
  We sought to clarify and investigate causative foods and mechanisms of FEIAn in a 14-year-old boy. In addition, we tested in vivo and in vitro effects of cromolyn sodium in the same patient.
  
  
  METHODS
  We used open challenge tests for the provocation of FEIAn and measured changes in plasma histamine levels and FEV1. In addition, we investigated the mechanism of FEIAn in this case with in vitro histamine release testing.
  
  
  RESULTS
  The patient was diagnosed as having FEIAn by provocation testing with a simultaneous intake of wheat and umeboshi, but not when each food was eaten singly, followed by exercise. In addition, his plasma histamine level increased transiently and forced expiratory volume 1, expressed as a percentage change from baseline, decreased significantly. A synergistic effect on in vitro histamine release testing with 2 kinds of the causative foods was shown. Administration of cromolyn sodium proved to be effective on both the in vitro and in vivo tests.
  
  
  CONCLUSIONS
  This is the first report of FEIAn provoked by the test with a simultaneous intake of 2 kinds of food. This case might in part explain negative challenge test results in patients with FEIAn.
authors.affiliation: Department of Pediatrics, Yokohama City University Medical Center, 4-57 Urafune-cho, Minami-ku, Yokohama 232-0024, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Aihara
authors.forename: T
authors.initials: T
authors.lastname: Kotoyori
authors.forename: Y
authors.initials: Y
authors.lastname: Takahashi
authors.forename: H
authors.initials: H
authors.lastname: Osuna
authors.forename: S
authors.initials: S
authors.lastname: Ohnuma
authors.forename: Z
authors.initials: Z
authors.lastname: Ikezawa
mesh_terms: D000293:Adolescent; D000707:Anaphylaxis / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology*; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D004205:Cromolyn Sodium / Q000627:therapeutic use; D015444:Exercise; D005512:Food Hypersensitivity / Q000150:complications* / Q000188:drug therapy; D005541:Forced Expiratory Volume / Q000276:immunology; D005638:Fruit / Q000009:adverse effects*; D006636:Histamine Release; D006801:Humans; D008297:Male; D014908:Triticum / Q000009:adverse effects*
chemical_list: D018927:Anti-Asthmatic Agents; D004205:Cromolyn Sodium