Incidence and source of hyperamylasemia after cardiac surgery.

We investigated the incidence and possible mechanisms of postoperative hyperamylasemia in 101 patients after cardiac surgery. Amylase (EC 3.2.1.1) activities in serum were increased in 36% of patients after bypass surgery, 59% of patients after valve replacement, and in 69% of patients after combined bypass and valve replacement. Lipase (EC 3.1.1.3) activity was increased in 30% of all patients. We found enzymatic evidence for pancreatitis in six patients. Thirty-six patients showed increased salivary (S-type) amylase activity, with a positive correlation (r = 0.55, P less than 0.001) between the severity of pleural effusions and the peak S-type amylase activity. Hyperamylasemia after cardiac surgery is apparently often related to absorption of S-type amylase from pleural fluid and (or) from aspirated salivary secretions. Monitoring patients for postsurgical pancreatitis necessitates assay of amylase isoenzymes to distinguish abnormalities resulting in release of pancreatic (P-type) amylase from those involving release of S-type amylase.