Biliary Alkaline Phosphatase Isoenzyme in Biliary Obstruction

Alkaline phosphatase (ALP; EC 3.1.3.1) is mainly derived from the liver, bones and in lesser amounts from intestines, placenta, kidneys and leukocytes. A raised level of alkaline phosphatase in the blood frequently indicates a variety of diseases. The examination of the ALP isoenzyme can be performed by electrophoresis. This examination can be helpful in disease classification of those cases with hyperalkalinephosphatasemia. Of several ALP isoenzymes, biliary ALP isoenzyme is mentioned for its clinical usefulness in detection of biliary obstruction. Here, the authors performed a study to investigate the clinical usefulness of biliary alkaline phosphatase isoenzyme in biliary obstruction. Of interest, there is no significant difference of serum ALP level between malignant and benign biliary obstruction group. But there is a significant difference of serum biliary - ALP isoenzyme between malignant (range 28 U/L 365 U/l) and benign biliary obstruction (range 20 140 U/L). Nevertheless, the average biliary - ALP level of the cholangiocarcinoma cases (range 105 365 U/L) is significant higher than the other malignant biliary obstruction cases (range 28 50 U/L). According to our study, the biliary - ALP isoenzyme determination can be use as a marker for malignant biliary obstruction.