[Single blind food challenge using dried food powder--1st report. Raw whole egg and egg yolk].

AIM: We have analyzed data of raw whole egg and egg yolk challenges performed in single-blinded manner. SUBJECTS AND METHODS: We have performed 92 whole egg challenges and 109 egg yolk challenges in admission from 1995 to 2005. RESULTS: The positive rate of whole egg challenges was 76.1%, and the most frequent symptoms seen during challenges involved gastrointestinal (GI) system, followed by skin, and respiratory system. The rate of anaphylaxis was 4.3%. Among 70 raw-egg positive cases, 62 heated-egg challenges were performed in open manner, which resulted in 18 negative cases (29%) against it. When we compared IgE CAP RAST against egg white between challenge positive cases and negative ones, IgE CAP RAST against egg white was significantly higher in positive group. With regards to yolk egg challenges, positive rate was 23.9%, and evoked symptoms were most frequently seen in skin, followed by GI system, and respiratory system. No case of anaphylaxis was observed. CONCLUSIONS: Single-blinded challenge tests against whole egg and egg yolk were useful for the diagnosis of pediatric egg allergy. IgE CAP RAST against egg white was useful when we considered timing of egg challenge tests. Among raw egg allergies, around 30% of patients could eat heated-whole egg. In order to improve egg allergy patients' quality of life, it is important to first introduce egg yolk challenges followed by heated-whole egg challenges, and finally raw-egg challenges, if it is necessary, in blinded manner.