Clinical relevance of alkaline phosphatase isoenzyme determinations by high performance liquid chromatography.

A new method for the separation of alkaline phosphatase isoenzymes by means of high performance liquid chromatography (HPLC) is presented. One isoenzyme was identified in homogenate of small intestine, two were identified in bone, and two in liver, and fragment and biliary isoenzymes were identified in bile. Sera from 32 patients with different diseases of the skeletal system or the liver were analysed. High activities of the bone isoenzymes were detected in bone diseases, of the second liver isoenzyme in acute hepatitis and of the first liver and biliary isoenzymes in biliary obstruction. There are indications that the first liver isoenzyme is derived from the cell membrane and the second liver isoenzyme from the cytosol. The biliary isoenzyme is considered to be a highly sensitive and specific indicator for cholestasis.