Concentrations of cyanocobalamin (vitamin B12) in serum have been found to be elevated in acute1-4 and chronic2,5,6 liver disease associated with hepatocellular damage. In acute viral hepatitis the rise in serum cyanocobalamin was most pronounced in the first two weeks of the disease, when bilirubinemia is marked and the liver-function tests indicative of hepatocellular damage are positive. In cirrhosis of the liver elevated cyanocobalamin values were found when clinical and laboratory signs of active hepatitis were present. In extrahepatic obstructive jaundice the serum cyanocobalamin level was found to be normal.1,3
These studies were extended to a larger group of patients. The serum cyanocobalamin values were correlated with the common liver-function tests and particularly with the degree and duration of bilirubinemia. It appeared from these studies that the estimation of serum cyanocobalamin may serve as an early and sensitive test for differentiating the various types of jaundice.