Diagnostic importance of changes in circulating concentrations of immunoreactive trypsin.

A specific and sensitive radioimmunoassay (R.I.A.) has been developed which makes possible the determination of serum or plasma trypsin concentrations despite the presence of trypsin inhibitors, which have invaldiated previously available enzymatic techniques. The assay was most precise at about 300 microng trypsin standard Ag5 per litre of serum, a value comparable with the mean in 76 healthy volunteers (273 microng/1) and in 20 hospital patients with non-pancreatic disease (266 microng/1). Markedly raised concentrations (970-6500 microng/1) were found in all 14 patients with acute pancreatitis and in 8 patients with chronic renal failure (580-1360 microng/1). Abnormal concentrations were found in 11 of 16 patients (69%) with pancreatic cancer (8 high, 3 low) and in 15 of 23 patients (65%) with chronic pancreatitis (3 high, 12 low). Patients with jaundice had normal or marginally lower than normal concentrations unless pancreatic disease or common-duct gallstones were present.