Isoenzymes of alkaline phosphatase in the serum of patients with cystic fibrosis.

In 36 children with cystic fibrosis (CF) the isoenzymes of alkaline phosphatase (AP) were determined microelectrophoretically in polyacrylamide- and starch-gel. The study was done to evaluate the clinical significance of these additional data for the diagnosis of liver involvement in DF. The results led to the following conclusions: 1. Serum activity of total AP is comparatively unsensitive "masking" alterations in the isoenzyme pattern contributing to the AP serum activity. 2. In 17 children resp. 47% bile-duct phosphatase was increased indicating a secretostasis while other marker enzymes of cholestasis were normal in part. 3. The activity of bone phosphatase in the serum showed a significant correlation to the degree of growth retardation in these patients. 4. Intestinal phosphatase was present in the serum of only one child with cirrhosis of the liver being an indicator for liver insufficiency. 5. Determination of AP isoenzymes in the serum may provide additional information about the organs involved for the physician in handling CF patients.