Impaired response of main pancreatic duct to secretin stimulation in early chronic pancreatitis.

In the present study we compared sonographic measurements of the main pancreatic duct (MPD) following maximal secretin stimulation (75 CU intravenous in 1 min) in 15 chronic pancreatitis patients (CP) with those of 18 normal control subjects. The mean caliber of the main pancreatic duct was 1.2 +/- 0.4 mm in controls and 1.8 +/- 0.9 in patients with chronic pancreatitis (P less than 0.025). In the control group a dilatation of the duct with a peak at the third minute was found. In patients with chronic pancreatitis a flatter profile of the response curve with a slower increase and inconstant return to basal values was found. A statistically significant difference was found between absolute variations of MPD caliber over basal values (1.7 +/- 1.06 in controls vs 0.8 +/- 0.69 in CP, P less than 0.005) and the dilatation index [(Dmax - D)/D] (1.31 +/- 0.6 in controls vs 0.66 +/- 0.69 in CP, P less than 0.005). The mean percent increase at the third minute was 131% in control subjects vs 53% of patients with CP (P less than 0.0005). In the five cases of CP showing a caliber increase greater than 100%, a persistent dilatation (100-200%) was found 15 min after secretin administration. At this time, the mean percent increase over basal value in controls was 25%.(ABSTRACT TRUNCATED AT 250 WORDS)