Tryptase and histamine metabolites as diagnostic indicators of indolent systemic mastocytosis without skin lesions

Abstract

In suspected patients without UP, the ISM risk is very low (if present at all) if tryptase is <10 μg/l. If tryptase is ≥10 μg/l, this risk depends on MIMA and MH, being low if these are normal, but high if these are elevated. Male gender and insect venom anaphylaxis are additional risk indicators. We recommend refraining from bone marrow examinations in suspected patients without UP if tryptase is <10 μg/l. Our results question the reliability of the minor diagnostic World Health Organization criterion of tryptase >20 μg/l.