The role of serum tryptase in COVID-19 pathogenesis and its value as a prognostic marker: a single-center prospective cohort study

Background Dysregulated inflammation is central to COVID-19 pathogenesis. Mast cells (MCs) and their protease tryptase are implicated in tissue injury and vascular dysfunction, but the prognostic value of circulating tryptase in COVID-19 remains uncertain. Methods We conducted a prospective cohort study including 82 patients with laboratory-confirmed COVID-19 admitted between January and March 2021. On admission, serum tryptase, C-reactive protein (CRP), procalcitonin (PCT), lactate dehydrogenase (LDH), and lymphocyte counts were measured. The objective of this study was to assess whether serum tryptase levels measured upon hospital admission are associated with COVID-19 severity and in-hospital mortality. Statistical analyses comprised t-tests, Mann–Whitney U tests, χ 2 tests, receiver operating characteristic (ROC) curve analysis, and logistic regression. Results Serum tryptase levels at admission did not differ significantly between patients requiring oxygen and those who did not (mean 5.45 vs. 4.97 μg/L; p = 0.2906) or between survivors and non-survivors (mean 5.24 vs. 5.60 μg/L; p = 0.6486). ROC analysis confirmed limited prognostic performance for tryptase regarding oxygen requirement (AUC = 0.580; p = 0.2972) and mortality (AUC = 0.538; p = 0.6103). By contrast, CRP, PCT, and LDH correlated strongly with disease severity. Elevated PCT (p = 0.0016) and LDH (p = 0.0360) were significantly associated with mortality. Logistic regression showed no independent association between tryptase and adverse outcomes. Conclusion In this prospective cohort, serum tryptase measured at admission was not associated with COVID-19 severity or mortality, suggesting limited utility as a prognostic biomarker. Established markers, particularly PCT and LDH, outperformed tryptase in predicting adverse clinical outcomes. The negative findings are clinically relevant as they demonstrate that tryptase does not contribute to prognostic risk stratification in COVID-19, and its measurement does not provide added value beyond standard inflammatory biomarkers.