Identification of amylase isoenzymes in intestinal contents.

Samples of intestinal contents were obtained from 16 patients: 5 from the midjejunum, 10 from the distal ileum, and 1 from the cecum. The presence of pancreatic and nonpancreatic isoamylases in these fluids was evaluated by an inhibitor assay (Pharmacia Corporation) and by polyacrylamide gel electrophoresis. In every sample the inhibitor assay detected the presence of pancreatic-type isoamylase but not salivary-type isoamylase. Electrophoresis confirmed that salivary-type isoamylase was totally absent. Therefore, in intestinal disorders which disrupt the intestinal mucosal barrier (such as ischemia, perforation, ulceration, or obstruction), the amylase which escapes from the intestinal lumen and is reabsorbed into the circulation is likely to consist entirely of pancreatic-type isoamylases. In these circumstances, measurement of serum amylase isoenzymes will not distinguish acute pancreatitis from an acute intraabdominal catastrophe requiring surgery.