Studies on Histamine Metabolism in Allergen‐Induced Asthma

Abstract
The excretion of histamine (Hi) and its metabolite methythistamine (MeHi)was determined in separated fractions of urine up to 12h alter standardized allergen provocations in 18 adult patients wild defined extrinsic bronchial asthma. The main histamine metabolite, methylimidazoleacetic acid (MelmAA), was measured in six of the patients.After positive provocations (decrease in FEV1> 20%) the excretion of Hi was significantly increased during 3h and that of MeHi during 4h after challenge. Negative provocations (decrease in FEV1in vivo.