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Tryptase levels predict severe or milk-induced anaphylaxis

Tryptase levels were successfully used to identify individuals with severe or milk-induced anaphylaxis, according to a single-institution study.

“Assessing the difference between reaction and postreaction tryptase levels may improve diagnostic sensitivity,” Sarah De Schryver, MD, of the division of allergy and clinical immunology, department of pediatrics at Montreal Children’s Hospital, and colleagues wrote.

De Schryver and colleagues evaluated the serum tryptase levels of 203 children who came to Montreal Children’s Hospital with anaphylaxis during a 4-year period.

The researchers measured the serum tryptase levels during the reaction, as well as during 9-month follow-up. They used multivariate linear and logistic regressions to evaluate the association between tryptase levels and various risk factors.

The investigators defined elevated tryptase levels as at least 11.4 μg/L during the reaction and — for study participants with a baseline levels — a reaction level of at least 2 ng/mL plus the value of 1.2 times the postreaction tryptase level.

Thirty-nine children (19.2%; 95% CI, 14.1-25.4) had elevated tryptase levels. Researchers determined only severe reactions were associated with reaction levels of at least 11.4 μg/L or higher (OR = 6.5; 95% CI, 2.2-19).

Milk-induced anaphylaxis (beta-adjusted = 4; 95% CI, 0.95-7) and severe reactions (beta-adjusted = 7.5; 95% CI, 4.8-10.3) also were associated with increased tryptase levels.

Reaction levels that exceeded the threshold level of 2 ng/mL plus the value of 1.2 times the postreaction tryptase level identified most anaphylaxis reactions, especially if baseline levels were measured 2 months or less after the reaction. – by Jeff Craven

Disclosure: The researchers report grants from The Allergy, Genes and Environment Network, Health Canada and Sanofi.