Total serum tryptase levels are significantly higher in younger infants compared with older ones. In infants of the same age, serum tryptase levels may vary according to the clinical condition and thus suggest mast cell involvement in the physiologic as well as in the allergic immune responses of young infants.

Purpose of review Serum tryptase, a mast cell marker, provides clues for the mechanism, severity, and management of drug hypersensitivity induced by immunoglobulin E dependent or independent mast cell activation. Recent findings The interpretation of serum tryptase levels has been challenged during the last 2 years by major advances in tryptase genetics and their rapid incorporation into clinical practice. On the contrary, new pathophysiological insight into nonmast cell-dependent immediate hypersensitivity has been gained. Summary This review provides up-to-date information on the pathophysiology and recommended use and interpretation of tryptase in the context of drug hypersensitivity reactions as a function of their endotype.

BACKGROUND The primary objective of this study was to determine the severity and quality of life of adolescents with chronic urticaria using the Urticaria Severity Score (USS).