How to differ endogenous and exogenous histamine?

Answer 1

Histamine is a chemical and not a class of chemicals. Which means all histamine is the same. Histamine is a biogenic amine C5H9N3 derived from Histidine by the enzyme L-Histidine decarboxylase. It is a vasoactive amine and is found in nerve synapses, the brain, the gastrointestinal tract, in mast cells and basophils (which is what produces allergic reactions), and in other tissues. Exogenous sources of histamine would include spoiled fish and other meats where histidine is converted to histamine. To my knowledge there are no ways of differentiating endogenous and exogenous histamine because biochemically they are the same compound.