The urinary excretion of histamine in children.

The role of histamine in disease has long been a subject of speculation but until recently little was known about its metabolism because of difficulties in estimating the free, pharmacologically active form in body fluids (Gaddum, 1948, 1951). However, new methods for the separation and purification of histamine have made it possible to follow its excretion in the urine, where it occurs in free and conjugated forms (Anrep, Ayadi, Barsoum, Smith and Talaat, 1944; Roberts and Adam, 1950). Conjugated histamine, which is pharmacologically inactive, is mainly acetyl histamine (4(3-acetylaminoethyl)imidazole) and is formed by bacteria in the gut (Urbach, 1949). In adults the excretion of free histamine changes little from day to day but that of the conjugate varies between wide limits. When histamine is given by slow intravenous infusion, about 100 of the dose appears in the urine as free histamine and there is no detectable increase in the urinary conjugate. After oral administration, however, it appears in the urine mostly in the conjugated form (Adam, 1950). These facts suggest that the normal excretion of free histamine in the urine may represent the continuous formation or liberation of histamine in the tissues and that the excretion of the conjugate is related to the amount of free histamine in the alimentary tract. Little is known about the metabolism of histamine in childhood, and the object of the present investigation was to determine whether infants and children excrete histamine and, if so, the form and quantity in which it occurs. At the same time we investigated the urinary excretion of histamine in infantile gastroenteritis, since it has been suggested that the absorption of histamine from the intestine causes symptoms in this condition (Mellanby, 1916).