Timely diagnosis of systemic mastocytosis (SM) remains challenging due to care heterogeneity. We implemented a standardized approach for SM screening and diagnosis utilizing a novel healthcare system-wide international screening registry. A retrospective analysis assessed rates of SM, cutaneous mastocytosis (CM), and molecular diagnoses before and two years after care standardization. Accuracy of individual and combined SM screening tests - basal serum tryptase (BST) ≥11.5 and ≥20.0 ng/mL, …