Serum levels of immunoreactive PSTI in acute abdominal disorders, with special reference to a possible extrapancreatic PSTI production.

The concentration of the pancreatic secretory trypsin inhibitor (PSTI) was measured in serum from 360 patients with acute abdominal diseases. Elevated levels were found in acute pancreatitis, cholangitis, choledocholithiasis, acute cholecystitis, pancreatic pseudocyst, malignancy, renal failure and in several different inflammatory conditions not connected with the pancreas. The results suggest the possibility of an extra-pancreatic production of PSTI, especially since the changes seen over time do not favour leakage or reabsorption as the cause of the high PSTI levels seen in acute pancreatitis. PSTI rather behaves as an acute phase reactant, as judged from the parallelism in the reaction pattern with antichymotrypsin.