Egg, wheat, soy, fish and shellfish allergy: SAQ

This child has IgE-mediated egg allergy. Her history of moderate eczema, a reproducible immediate reaction (urticaria, angioedema and vomiting within twenty minutes) to scrambled egg, a skin-prick test of 5 mm and an egg-white specific IgE of 8 kU/L together meet the clinical and investigative criteria for egg allergy. The broad elimination diet her parents have adopted is not justified, because the other foods have not been shown to be allergic, and a confirmed allergy to one food does not imply allergy to the others. She needs a focused plan and the restoration of non-allergenic foods. ^[1]

Question 1 (10 marks)

Classify her reaction, justify the diagnosis, and outline the immediate management plan including dietary advice. (4 marks for classification and diagnosis; 3 marks for the management plan; 3 marks for dietary advice and correcting the elimination diet.) ^[2]

Her reaction is IgE-mediated, distinguished from non-IgE reactions by its rapid onset within minutes to two hours of exposure and its immediate phenotype of urticaria, angioedema and vomiting. The diagnosis is supported by the consistent history, a skin-prick test of 5 mm (above the 3 mm threshold) and a raised egg-white specific IgE of 8 kU/L, all of which indicate sensitisation that, combined with the convincing history, supports clinical egg allergy. The oral food challenge is the gold standard, but in this case the history and tests are sufficiently concordant that the diagnosis is established without challenge, and the priority is the management plan rather than further confirmation. ^[1]

The immediate management plan has three components. First, allergen avoidance of egg, with dietetic support to read labels for hidden egg (egg as a glaze, binder or in baked goods). Second, a written anaphylaxis action plan (the ASCIA plan in Australasia) and an adrenaline autoinjector, because she has had a systemic reaction; she is under 20 kg so the 0.15 mg device is appropriate. Third, family and carer education in recognising an early reaction and using the autoinjector, with a follow-up allergy appointment. ^[2]

The dietary advice must correct the over-broad elimination. There is no evidence of wheat, soy, fish or shellfish allergy, and removing them risks nutritional deficiency, growth faltering and unnecessary anxiety. These foods should be reintroduced. Egg remains the only confirmed allergen, and a supervised baked-egg challenge is appropriate, because many egg-allergic children tolerate extensively heated egg in a matrix such as a well-baked muffin, and regular baked-egg consumption can accelerate tolerance. A dietitian should oversee the reintroduction of the other foods and the baked-egg ladder. ^[1]