The measurement of pancreatic polypeptide is used in the detection of pancreatic tumors.
Pancreatic polypeptide (PP) is a 36-amino-acid peptide that is predominantly produced by the pancreas. Pancreatic polypeptide is secreted by the pancreas in response to hypoglycemia, ingestion of food, or when food is chewed but not swallowed, secondary to vagal nerve stimulation. The physiologic role of pancreatic polypeptide in healthy individuals is, among others, in the regulation of the secretion of pancreatic enzymes, water, and electrolytes. Pancreatic polypeptide increases gastric emptying and gut motility and relaxes the pyloric sphincter, the colon, and the gallbladder.
Pancreatic polypeptide levels increase after ingestion of food. Prolonged fasting, diabetes, and advanced age can also increase pancreatic polypeptide levels. Pancreatic polypeptide levels can be elevated in patients with carcinoid syndrome, in patients with duodenal ulcers, and in patients with type I diabetes.
Pancreatic polypeptide secretion can be increased by endocrine-active tumors of the pancreas. Tumors that secrete only pancreatic polypeptide are rare. Pancreatic polypeptide levels are often elevated in patients with VIPomas, glucagonomas, gastrinomas, and insulinomas.