What Is a Pancreatic Polypeptide?

Pancreatic polypeptide is part of the pancreatic hormone family. It is typically accompanied by neuropeptide Y and peptide YY. Of the three, pancreatic polypeptide was the first to be discovered. It contains 36 amino acids and is located not only in the pancreas, but also in the stomach and gastrointestinal tract.

Activity in the gall bladder, pancreas, and intestines is slowed by pancreatic polypeptide. In addition, it stimulates the colon to contract. Metabolic functions are affected by the secretion of pancreatic polypeptide, and it may also reduce metabolic energy and decrease the level of fatty acids in the body. Research has shown patients with anorexia typically have a decreased level of pancreatic polypeptide in their systems. It has also been shown to be present in patients with rare cancerous tumors called PPomas.

Patients with pancreatic cancer typically have increased levels of PP in their systems. In some cases, those increased levels are the first indicator that a tumor is present. Pancreatic polypeptide also makes itself known when gallstones block the ducts.

Pancreatic polypeptide was first discovered in 1972 by colleagues working in different laboratories. Ninety-three percent of PPs are located in the pancreas and are also known as F-cells. Watery diarrhea, when accompanied by certain tumors of the body, may be caused by pancreatic polypeptide.

Diagnosing PP is difficult, with a 50 to 60 percent accuracy. An exception to the low diagnostic rate is the case of renal failure, which typically produces elevated levels of PP. In addition, elderly men with endocrine tumors often present with elevated levels of PP in their test results. Pancreatic tumors show elevated levels of PP 20 to 67 percent of the time. Some healthcare professionals believe exploratory tests should be ordered any time a patient presents with elevated levels of PP, while others take a wait-and-see approach if a tumor cannot be located.