What is Histamine, Urine?
Histamine is synthesised from L-histidine by histidine decarboxylase in mast cells, basophils, gastric enterochromaffin-like cells, and intestinal bacteria. Urinary histamine reflects peripheral histamine production and catabolism — gut microbiome composition and dietary histamine load are the dominant determinants of urinary output. Central histaminergic neurons (arising from the tuberomammillary nucleus of the posterior hypothalamus and projecting throughout the brain) regulate the sleep-wake cycle, appetite, and cognitive alertness, though they contribute negligibly to urinary histamine output.