Pancreatic Polypeptide

Serum, frozen

0.5 mL

0.3 mL (Note: This volume does not allow for repeat testing.)

Red-top tube or gel-barrier tube

Patients should fast for 10 hours prior to specimen collection. No radioisotopes should be administered during the 24 hours prior to specimen collection.

Support a diagnosis of pancreatic endocrine tumors

Results of this test are labeled for research purposes only by the assay's manufacturer. The performance characteristics of this assay have not been established by the manufacturer. The result should not be used for treatment or for diagnostic purposes without confirmation of the diagnosis by another medically established diagnostic product or procedure. The performance characteristics were determined by LabCorp.

Radioimmunoassay (RIA)

0.0−418.0 pg/mL

Pancreatic polypeptide (PP) is a 36-amino-acid secretory peptide that is predominantly produced by the pancreas.¹ The exact physiologic role of PP in healthy individuals has not been fully defined.^1,2 It has been shown, however, that this peptide affects the secretion of pancreatic enzymes, water, and electrolytes.¹ Its effect is biphasic in that PP initially enhances secretion and then inhibits secretion.¹ PP increases gastric emptying and gut motility.¹ It also relaxes the pyloric and ileocecocolic sphincters, the colon, and gallbladder.¹ PP levels increase after ingestion of food and remain elevated from 4-8 hours.^1-3 Prolonged fasting, diabetes, and exercise can also increase PP levels.^2,3 Serum PP levels can be elevated in as many as 50% of patients with carcinoid syndrome.³ Increased levels can also be found in patients with duodenal ulcers and in patients with type I diabetes.¹ PP levels are often low in patients with pancreatic insufficiency or pancreatitis.¹

PP secretion can be increased by endocrine-active tumors of the pancreas.^2-5 Tumors that secrete only PP are rare with only 22 cases reported in the literature.^2,4 Seven of the reported cases developed a watery diarrhea hypokalemia achlorhydria (WDHA) syndrome, also referred to as Verner-Morrison syndrome, that is similar to that seen in VIPomas.² Another five reported cases had steatorrhea.² The last ten had silent or nonfunctioning tumors without hormone-related symptoms.²

Increased PP secretion has been frequently reported in patients with functioning and nonfunctioning pancreatic tumors that produce other endocrine peptides.^1-5 PP levels are often elevated in patients with VIPomas, glucagonomas, gastrinomas, and insulinomas.^1,2,5 Eriksson and colleagues found that PP levels were elevated in 74% of patients with endocrine pancreatic tumors and that this peptide serves as a good general marker for patients suspected of having pancreatic endocrine tumors.⁵