Histamine Metabolism in Patients with Histidinemia: Determination of Urinary Levels of Histamine, N^τ-Methylhistamine, Imidazole Acetic Acid, and Its Conjugate (s)

Abstract

Histamine metabolism in histidinemic patients was studied by measuring the urinary levels of histamine and its metabolites. The urinary excretions of histamine, N^τ-methyl histamine, imidazole acetic acid, and its conjugate (s) were higher in patients with histidinemia than in controls, and these levels of excretion were correlated with the plasma histidine level. The urinary histamine levels of patients with eczema-like dermatitis were twice that of those without dermatitis. The urinary excretion of 3-methylhistidine showed a close correlation with the urinary histidine excretion. Thus, it was concluded that histamine metabolism is higher in histidinemic patients than in normal controls.