Basal and postatropine serum pancreatic polypeptide concentrations in familial multiple endocrine neoplasia type I

The present study was undertaken to determine the value of measurement of basal and postatropine serum pancreatic polypeptide (PP) levels for the diagnosis of endocrine pancreatic tumors in affected members of families with multiple endocrine neoplasia type I (MEN I). Basal serum PP levels were elevated in 3 of 19 affected members of 6 families with MEN I. The 3 patients with elevated serum PP (115--157 pmol/liter) had evidence of gastrin-producing tumors. In 5 other patients with evidence of gastrinoma from MEN I families serum PP levels were normal. All 11 family members affected with MEN I without pancreatic tumors had normal serum PP concentrations. Intravenous administration of 1 mg atropine to all 19 affected members of MEN I families and to 8 normal control subjects inhibited serum PP in all of them. Serum PP in the 3 MEN I patients with elevated PP decreased markedly in response to atropine but remained higher than the postatropine serum PP concentrations in the other subjects. It is concluded that an elevated serum PP is a relatively insensitive marker for endocrine pancreatic tumors in MEN I. The observation that atropine inhibits serum PP levels in MEN I patients with endocrine pancreatic tumors throws doubt on the clinical usefulness of an atropine suppression test for PP in the diagnosis of pancreatic endocrine tumors.