Serum tryptase as a biomarker of anaphylaxis in children in real clinical practice

BACKGROUND: Anaphylaxis is a severe, life-threatening systemic allergic reaction. Currently, the only biomarker of anaphylaxis recommended for use in Russian and international consensus documents is tryptase, with very limited data on the efficacy of its use in real clinical practice in children. AIM: To determine the frequency of measurement and diagnostic significance of tryptase level estimation in children with anaphylaxis within the recommended time frame in real clinical practice, as well as its relationship with the age of patients and the severity of symptoms. METHODS: The study included 128 patients aged 0 to 18 years who were hospitalized urgently in the State Budgetary Institution Morozov Children’s City Clinical Hospital due to an episode of anaphylaxis in the period from May 2022 to April 2025 and were included in the Pediatric Moscow Anaphylaxis Register. The diagnosis of anaphylaxis was verified by an expert allergist-immunologist based on clinical criteria for anaphylaxis. Serum tryptase levels were measured in patients admitted to the hospital within 3 hours of the onset of symptoms of acute allergic reaction. The patients’ clinical and laboratory parameters were entered into an online registry questionnaire and processed using a computer program, which is a system for data recording and analysis. RESULTS: Of the 128 children, 52 (40.6 %) had their tryptase levels measured within 3 hours of symptom onset. Among these, 15 (28.8 %) showed elevated tryptase levels. For the 76 children who were not assessed (due to delayed hospitalization), a higher frequency of mild anaphylaxis was observed compared to those assessed for tryptase levels (31.6 % vs 15.4 %; p = 0.037). No correlation was found between age and tryptase levels, though there was a trend toward older patients (median 12 years vs 10 years; p = 0.052) being within the timeframe for tryptase measurement. Severity of reaction did not affect tryptase concentrations. CONCLUSION: In clinical practice, tryptase levels can be measured within 3 hours of symptom onset in less than half of patients, with only one third showing elevated levels. Delayed hospital arrival in patients with mild anaphylaxis is likely to delay diagnosis and treatment.