Disproportionate reduction in tryptic response to endogenous compared with exogenous stimulation in chronic pancreatitis.

The secretin-pancreozymin (SP) and Lundh-Borgström (meal) tests were compared in diagnosing chronic pancreatitis (CP). A range of normal values for each test was obtained in a control group of 22 patients without pancreatic disease. Seventeen patients with CP were given the tests on separate days. The peak concentration of bicarbonate after secretin was reduced in 14 of these 17 patients, post-secretin bicarbonate output fell in 13, while peak tryptic activity (PTA) in duodenal juice after pancreozymin was below normal in 10; the overall incidence of abnormal results in SP tests was 88%. The mean tryptic activity (MTA) in a two-hour collection of duodenal juice after the test meal was reduced below normal in 16 of the 17 patients.In the control group PTA after pancreozymin was closely similar to MTA after the test meal, but in the patients with CP MTA was significantly less than PTA. PTA and MTA correlated significantly in both the control and CP groups, and the slopes of the two regression lines were not significantly different. In each patient with CP the tryptic response to the test meal was only a third of the tryptic response to intravenous pancreozymin. This disproportionate reduction in tryptic response to endogenous compared with exogenous stimulation in CP accounts for the high success rate of the meal test, which equalled the SP test.The Lundh-Borgström test is a sensitive indicator of CP and is within the resources of most hospitals. The SP test is better suited to specialist centres and may provide valuable additional information in individual cases.