Friday, August 30, 2024

Unexpected allergic reaction

Q: 23 years old male with some undefined allergic reactions in the past was admitted to ICU with severe systemic allergic reaction after an insect bite, which required administration of an "epi injection." Which one blood test should be sent to rule out mast cell disorders (Mastocytosis)?


Answer: Tryptase level

This question aims to emphasize the typical outcome of regular insect bites. Systemic allergic reactions to insect bites are uncommon. Still, patients with mast cell disorders may develop severe systemic allergic reactions following insect bites or minor triggers for which severe reactions are unexpected.

During any such episode, serum total tryptase should be checked to establish the diagnosis of mastocytosis. Tryptase levels above 5-8 ng/mL are considered a risk. These patients, even though they may not have underlying systemic mastocytosis, are always at high risk for severe allergic reactions. Proper prevention and availability of an "epi-pen" can be a lifesaver. Patient should be referred to an allergist.


#allergy-immunology


References:

1. Reiter N, Reiter M, Altrichter S, et al. Anaphylaxis caused by mosquito allergy in systemic mastocytosis. Lancet 2013; 382:1380.

2. Ruëff F, Przybilla B, Biló MB, et al. Predictors of severe systemic anaphylactic reactions in patients with Hymenoptera venom allergy: importance of baseline serum tryptase-a study of the European Academy of Allergology and Clinical Immunology Interest Group on Insect Venom Hypersensitivity. J Allergy Clin Immunol 2009; 124:1047.

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