[Alkaline phosphatase isoenzymes. Selection of the seperation methods and their diagnostic value]

Polyacrylamide gel electrophoresis (PAGE) of alkaline phosphatase (AP) was performed in 116 patients with elevated AP and in 36 controls. Results were compared with clinical data and with the heat inactivation techniques for AP isoenzyme separation. This latter method is simple but approximate; it is without value in the case of coexistent bone and liver pathology. PAGE gave a clear separation of liver, bile, bone, and intestinal AP isoenzymes. Disagreement with clinical data was rare (6 out of 86) and occurred in cases of associated bone and liver pathology (with 1 exception only), where one of these two abnormalities was not detected. Heat inactivation is useful as a screening test. If the cause of the elevated AP remains unknown after a few simple examinations, PAGE should then be utilized. Although more time-consuming, it is certainly more effective in the separation of AP isoenzymes.