Alkaline phosphatase is one of the liver function tests. If alkaline phosphatase is simply elevated, it is usually of little clinical significance. However, alkaline phosphatase can be an early indicator of liver disease and skeletal disease. If the patient has liver disease, alkaline phosphatase and GGT are elevated. In addition, if there is an increase in direct bilirubin and total bilirubin, especially if the total bilirubin is above 34.2 μmol/L, obstructive jaundice due to obstructive factors is most often considered. Patients should have an ultrasound of the upper abdomen and, if necessary, MRCP water imaging of the biliary tract. This will usually detect whether the obstruction is due to a stone or tumor pressure in the bile duct. If it is a stone, the patient will also need to undergo ERCP to remove the stone. If the patient has high alkaline phosphatase on more than three consecutive retests to rule out liver system disease, the patient also needs to actively check the whole body skeletal system for any tumor disease of the skeletal system.