Serum tryptase and the laboratory diagnosis of systemic mastocytosis.

Total tryptase levels of 20 ng/mL or higher in a baseline serum sample when the ratio of total to beta-tryptase is 20 or greater strongly suggest underlying systemic mastocytosis. Whether these criteria prove to be more sensitive than a bone marrow biopsy will require further study. Although the absolute level of total tryptase does not predict disease severity, it may provide a practical method for assessing the efficacy of therapeutic interventions designed to reduce the mast cell burden.