Urinary excretion of histidine derivatives in megaloblastic anaemia and other conditions and comparison with the folic acid clearance test.

Urinary excretion of urocanic acid and formimino-glutamic acid in abnormal amounts following oral doses of histidine has been observed not only in most cases of megaloblastic anaemia, but in iron-deficiency anaemia, haemolytic anaemia, and neoplastic disease. The urinary excretion of these substances is increased in those disease states in which an abnormally rapid rate of removal from the plasma of intravenously injected folic acid has been demonstrated.