Severe acute pancreatitis and normal serum amylase activity due to pancreatic isoamylase deficiency.

A 31-year-old man with a primary attack of severe acute alcohol-induced pancreatitis presenting with a low to normal amylase activity in serum is described. The diagnosis was confirmed surgically and, further, by studies of immunoreactive trypsin in serum, which was elevated. Analysis of pancreatic isoamylase in serum during the convalescence showed very low activity. The patient is thought to represent a case of pancreatic isoamylase deficiency.