Abnormal pancreatic isoamylases in the serum of children with choledochal cyst

Purpose: To investigate the changes of pancreatic isoamylases in the serum of children with choledochal cyst. Methods: Serum and bile from 20 children with choledochal cyst were studied for total amylase activity and isoamylases. Using electrophoresis, the assay of pancreatic isoamylases was expressed by peak appearance rate (PAR) and ratio of isoenzyme activity (RIA). Serum from 20 healthy children and 12 adults with acute pancreatitis served as a comparison. Results: The total amylase activity in the serum of children with choledochal cyst was slightly higher than that of healthy controls, but dramatically lower than that of acute pancreatitis. The serum of children with choledochal cyst showed 5 pancreatic peaks (PAR: P1, 100%; P2, 100%; P3, 100%; P4, 75%; P5, 45%) without any major peak. In healthy controls, only P1 and P2 were present (PAR: P1, 40%; P2, 100%) with the latter being a major peak (RIA: 81.8 ± 25.3%). These results in children with choledochal cyst differed from those of patients with acute pancreatitis who presented with the less common P4 and no P5 (PAR: P1, 100%; P2, 100%; P3, 91.6%; P4, 8.3%). The pattern of pancreatic isoenzymes in bile was similar to that in the serum from patients with choledochal cyst. These abnormal pancreatic isoamylases gradually disappeared after operation. Conclusions: Abnormal pancreatic isoamylases, especially P4 and P5, are found in the serum of patients with choledochal cyst, which would point to a reflux of pancreatic juice into the biliary tract.