Factors influencing duodenal trypsin levels following a standard test meal as a test of pancreatic function

In this investigation, the measurement of trypsin levels in duodenal juice following a standard test meal (Lundh test) was evaluated as a test of pancreatic function, and a study was made of diseases and other factors which may influence its diagnostic efficiency. The method of trypsin assay, which required only basic laboratory equipment, gave a linear concentration-activity curve, with a threshold at 50 mug of crystalline trypsin per ml. Intestinal juice could be frozen and stored for up to six weeks with no detectable loss of tryptic activity. The normal control values were very similar to those found by other workers and were unaffected by the sex or age of the subject. When used to assess 32 patients in whom the presence or absence of pancreatic disease had been clearly established, the test had a diagnostic success rate of 94%. Retrospective analysis of results from 98 patients showed that trypsin levels were generally grossly reduced in patients with chronic pancreatitis or carcinoma of the head of the pancreas. Trypsin levels were normal in most patients with steatorrhoea not of pancreatic origin. Levels were generally depressed to intermediate levels in patients with a diabetic glucose tolerance, with or without steatorrhoea, but no other sign of pancreatic insufficiency. Some lowering of trypsin levels was also noted in patients having an obstruction of the common bile duct. A small but significant depression of tryptic activity was noted in patients with villous atrophy and no pancreatic disease.