To determine if the measurement of serum baseline tryptase (sBT) levels can accurately diagnose pediatric asthma and predict asthma severity.

The study included 114 asthmatic children between the ages of 5 and 12 years. Within the cohort, 36 children had mild intermittent asthma, 38 had mild persistent asthma, and 40 had moderate to severe persistent asthma. In addition, 34 age-matched healthy children were included as controls.

Serum baseline tryptase levels were measured in all asthmatic children and healthy controls. Asthma severity was assessed for asthmatic children using asthma serum markers (total IgE, interleukin-13, interferon-γ), childhood asthma control tests (C-ACT), GINA guideline–based severity evaluations, and pulmonary function tests. The diagnostic accuracy of sBT levels was assessed by receiver operating characteristic (ROC) analysis. The correlation between sBT levels and asthma severity was assessed by Pearson and Spearman correlation tests.

Median sBT levels were significantly greater in the mild persistent (4.2 µg; range 1.6–6.0) and severe persistent (4.7 µg; range 1.8–7.8) asthma groups compared with those with mild intermittent asthma and healthy controls. ROC curve analysis showed that sBT levels are both sensitive (75.4%) and specific (88.2%) in discriminating asthmatic children from healthy controls at a cut-off value of 3.2 µg. ROC curve analysis showed that sBT levels are considerably sensitive (85.9%) and specific (88.9%) in distinguishing patients with persistent asthma from intermittent asthma at a cut-off value of 3.6 µg. Correlation analysis revealed that sBT levels strongly correlated with C-ACT scores, serum IgE levels, eosinophil counts, pulmonary function parameters, and IL-13 levels in all asthma subgroups.

Serum blood tryptase levels may help support the diagnosis of asthma in children and predict disease severity.

Tryptase is a marker of human mast cell activation, and elevated levels have been associated with increased risk of insect venom hypersensitivity and anaphylaxis in children with food allergies. This is one of the first studies to suggest a role for serum blood tryptase levels in the diagnosis of asthma. This marker could support the diagnosis of asthma in pediatric patients who are too young for or are unable to complete pulmonary function tests.