Serial serum tryptase determination should include the peak tryptase value (optimally measured between 30 min and 2 h after the onset of symptoms) and a baseline value (accurate baseline values are measured best 48–72 h after the anaphylaxis episode) allowing a comparison between the peak and the baseline values.44 During IgE-mediated anaphylaxis, allergen-induced cross-linking of IgE-binding sites on mast cells is followed by an explosive release of granular mediators.41 This evidence concerns the gene IGHE and anaphylaxis.