Basal tryptase linked to severe reactions in children with sting allergy

By Mark Cowen, Senior medwireNews Reporter

Elevated levels of serum basal tryptase (sBT) are associated with an increased risk for systemic reactions in children with insect venom allergy, research shows.

Ayfer Tuncer (Hacettepe University Faculty of Medicine, Ankara, Turkey) and team also found that a sBT level of 4.8 µg/l or higher was a significant predictor of severe reactions in children with systemic reactions.

"Determination of sBT levels in children with venom allergy may help clinicians to detect and inform the patients under risk of severe systemic reactions and optimal and timely use of therapeutic interventions in children," they comment in Allergy.

The researchers studied 128 children, aged a median of 8.9 years, with insect venom allergy and 55 age- and gender-matched control children without a history of reactions to insect stings.

Of the children with venom allergy, 55 had a history of systemic reactions and 18 had a history of large local reactions (LLRs). And of the children with a history of systemic reactions, 24 (44%) had experienced severe reactions.

Analysis of blood samples taken from the participants revealed that median sBT levels were significantly higher in children with systemic reactions than in those with LLRs and controls, at 4.2 versus 3.1 and 2.9 µg/L, respectively.

Further analysis revealed that a sBT cutoff point of 4.8 µg/L had the highest combined sensitivity, specificity, positive predictive value, and negative predictive value for severe reactions in patients with systemic reactions, at 5.8%, 87.1%, 73.3%, and 67.5%, respectively.

Indeed, children with severe systemic reactions were significantly more likely to have sBT levels above 4.8 µg/L than those with mild systemic reactions, at 46% versus 13%.

Tuncer et al conclude: "Our results indicate that [increased] sBT levels are associated with a higher risk of severe systemic reactions in children with insect venom hypersensitivity."

They add: "Our findings may encourage physicians to initiate venom immunotherapy particularly in children with sBT levels higher than 4.8 µg/l and with a history of mild systemic reactions after stings. Further studies with larger study populations may be required to reconfirm this finding."

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