C-peptide concentration in pancreatic juice obtained during endoscopic pancreatography in patients with and without insulinoma.

ERCP was performed in three patients with insulinoma. One had a large malignant tumor, while the remaining two had small tumours. In two of these patients pancreatic juice was collected for C-peptide determination. Pancreatography was performed and pancreatic juice was obtained in seven other subjects comprising: five control subjects and two patients in whom insulinoma was suspected because of symptoms suggestive of hypoglycaemia. Pancreatography was normal in all subjects except the patient with a large insulinoma in whom an obstruction of the main pancreatic duct was found. The maximal C-peptide concentrations in pancreatic juice of patients with insulinoma were found to be several-fold higher than in the control subjects and in one of the patients in whom insulinoma was suspected but unproven. The remaining patient with suspected insulinoma had a maximal C-peptide concentration comparable with those found in patients with proven insulinoma. Thus remarkable differences in maximal C-peptide concentrations obtained in patients with and without insulinoma were found. However, the clinical significance of the findings needs further evaluation. The value of ERP in patients with suspected insulinoma may be twofold: an obstruction of the main pancreatic duct may indicate a large, hardly resectable tumour; in patients in whom the duct is unaffected the relation between the tumour as visualized by angiography, and the duct, is of value for the surgeon when planning the operation.