Lv. Studies on Bile Pigments

THE study of bile pigment derivatives is important because these substances represent the end-products of haemoglobin metabolism. The destruction of haemoglobin both normal and pathological can thus be measured by quantitative determination of the urobilin and urobilinogen in urine and faeces. On the other hand, when pathological destruction of haemoglobin can be excluded, urobilinor urobilinogen-uria indicates failure of the liver to take up these substances from the portal circulation. Thus the test is valuable in the study of both blood and liver diseases. In the present work the Ehrlich-Neubauer colour reaction for urobilinogen with p-dimethylaminobenza]dehyde in HCI and the Jaffe-Schlesinger fluorescence reaction with zinc-acetate-alcohol for urobilin have been studied as qualitative urine tests. Neubauer [1903] identified urobilinogen as the reacting substance in Ehrlich's aldehyde test but described also positive reactions with other pyrrole derivatives such as reduced haematin and haemopyrrole. Thomas [1907] summarised the chemical properties of urobilin and urobilinogen and mentions indole and tryptophan as interfering substances. Fischer and Meyer-Betz [1911; 1912] first isolated urobilinogen from a pathological urine and assumed this substance to be identical with mesobilirubinogen prepared from bilirubin. Watson [1932; 1933] and Lemberg [1934] however stated that urobilinogen is not identical with mesobilirubinogen which differs from the former in its characteristic violet iron reaction. The quantitative estimation has been greatly improved by Charnass [1909] who first applied Ehrlich's test quantitatively instead of using the less stable urobilin reactions. Terwen [1924] devised a quantitative method introducing ferrous salts for the reduction of urobilin.