Tryptase is the most abundant mediator stored in mast cells. While its biological function has not been fully clarified, mast cell tryptase has an important role in inflammation and servers as a marker of mast cell activation. Serum tryptase concentration is increased in anaphylaxis and anaphylactoid reactions. However, it might fail to increase in food anaphylaxis or might increase in other allergic conditions, systemic mastocytosis and other hematological conditions. We aimed to investigate the clinical significance of serum tryptase.
We conducted a retrospective analysis of medical records of 105 subjects who performed serum tryptase levels.
Anaphylaxis was 84 (80%) and urticarial/angioedema 7 (6.7%), food allergy 3 (2.9%), allergic diseases 3 (2.9%), and others 8 (7.6%). Subjects with high tryptase levels ( >12 ㎍/L ) were 20 (19%), and all the subjects were anaphylaxis. Anaphylaxis group showed significantly higher tryptase levels than nonanaphylaxis group (12.94±20.38 ㎍/L vs 3.92±2.2 ㎍/L, P=0.028). Among anaphylaxis subjects, there was no significant difference in the cause and clinical manifestations of anaphylaxis between high tryptase group (64/84, 76.2%) and low tryptase group (20/84, 23.8%). The number of blood samples obtained <6hr after the onset of the reaction was significantly higher in high tryptase group compared with low tryptase group among total subjects (80% vs 23.5%, P<0.001) and anaphylaxis subjects (80% vs 21.9%, P<0.001), except between anaphylaxis group and nonanaphylaxis group.
Elevated tryptase levels are highly suggestive of anaphylaxis. The proper timing of blood sampling for tryptase is important to diagnose anaphylaxis.