Significance of Serum Leucine Aminopeptidase Isozyme in Hepatobiliary Diseases

The serum LAP zymograms of 140 cases of hepatobiliary diseases were examined. Normal cases show only one activity bands, but 48 % of cases of hepatobiliary diseases showed 2 or 3 activity bands. The appearance of this pathological LAP isozyme is not necessarily parallel to increases in serum LAP activity or bilirubin concentration. A certain degree of hepatic parenchymal disturbances is necessary for pathological isozyme to appear. However, when there is no bile duct obstruction, no matter how severe parenchymal disturbances may be, no pathological isozyme appears. This pathological isozyme is almost specific to obstruction of the bile duct. When an icteric patient shows 2 pathological serum isozymes, there is a very strong possibility of this cse being probable cholelithiasis of malignant bile duct obstruction. Case of bile duct obstruction with no increase of serum GPT show only one pathological LAP isozyme and those which have increased serum GPT show 2pathological isozymes.