Formerly the occurrence of either bile pigments or bile salts in the blood would have been regarded as indicative of abnormal conditions. The bile pigments were assumed to be formed almost exclusively in the liver from hemoglobin liberated on disintegration of red blood cells and then discharged in the bile. Bile pigments in the blood thus became an index of some interference with the normal secretion and discharge of the hepatic secretion in which they are present. Today, thanks to the work of several investigators, it seems assured that bile pigments may have an extrahepatogenous origin. They can be formed in the body even under conditions in which the liver is excluded from participation. The occurrence of bile pigment in the blood in some quantity thus becomes an inevitable consequence; abnormality consists in an excessive content in the circulating medium.
The Alleged Presence of Bile Salts in Blood. JAMA. 2014;311(24):2548. doi:10.1001/jama.2014.6380