Secretin dose-response in health and chronic pancreatic inflammatory disease

Stepwise increasing doses of secretin (0.078, 0.233, 0.7, and 2.1 U/kg-h) were given to 12 healthy volunteers (HV) and to patients with a history of chronic pancreatic inflammatory disease of more than five years (CP5, 12 patients) and two years or less (CP2, 9 patients). The maximal bicarbonate response (Vmax) and the half maximal dose of secretin (Km) were calculated for each individual. Bicarbonate responses below that in HV were found in the majority of CP5 and in one-third of CP2. Vmax showed no superiority to the responses to the three largest doses of secretin in the diagnosis of bicarbonate secretory deficiency. In CP2 bicarbonate responses above that in HV were frequently found with the small doses of secretin. No evidence of hypersecretion was found. The findings suggested, however, that the early stage of chronic pancreatic inflammatory disease may be associated with an increased sensitivity to secretin. Km was poorly reproducible and showed no diagnostic ability. Large doses of secretin stimulated the secretion of proteolytic enzymes, but the diagnostic efficiency was less than for bicarbonate. The output of calcium varied markedly in CP2 and CP5. The bicarbonate/calcium ratio, however, was almost invariably lowered in these patients and showed diagnostic superiority to bicarbonate secretion.