Pancreatic Polypeptide

CPT Test code: 83519

Related Information:	Gastrin, Serum Glucagon, Plasma Insulin Vasoactive Intestinal Polypeptide (VIP), Plasma
Specimen:	Serum, frozen
Volume:	0.5 mL
Minimum Volume:	0.3 mL (Note: This volume does not allow for repeat testing.)
Container:	Red-top tube or gel-barrier tube
Special Instructions:	Values obtained with different assay methods should not be used interchangeably in serial testing. It is recommended that only one assay method be used consistently to monitor each patient’s course of therapy. This procedure does not provide serial monitoring; it is intended for one-time use only. If serial monitoring is required, please use the serial monitoring number 480704 to order.
Collection:	Transfer the serum into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N^o 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Storage Instructions:	Freeze within four hours of collection.
Patient Preparation:	Patients should fast for 10 hours prior to specimen collection. No radioisotopes should be administered during the 24 hours prior to specimen collection.
Causes for Rejection:	Recently administered isotopes; specimen not frozen; specimen not serum
Reference Interval:	0.0-418.0 pg/mL
Use:	Support a diagnosis of pancreatic endocrine tumors
Limitations:	This procedure may be considered by Medicare and other carriers as investigational and, therefore, may not be payable as a covered benefit for patients.
Additional Information:	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.¹PP 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
Footnotes:	1. Henderson RA, Rinker AD, “Gastric, Pancreatic and Intestinal Function,” Burtis CA, Ashwood ER, eds, Tietz Textbook of Clinical Chemistry, 3rd ed, Philadelphia, PA: WB Saunders Co, 1999, 1271-1327.2. Pasieka JL, Hershfield N, “Pancreatic Polypeptide Hyperplasia Causing Watery Diarrhea Syndrome: A Case Report,” Can J Surg, 1999, 42(1):55-8 (review). PubMed 10071589 3. Vinik AI, Strodel WE, Eckhauser FE, et al, “Somatostatinomas, PPomas, Neurotensinomas,” Semin Oncol, 1987, 14(3):263-81. PubMed 2820062 4. Bellows C, Haque S, Jaffe B, “Pancreatic Polypeptide Islet Cell Tumor: Case Report and Review of the Literature,” J Gastrointest Surg, 1998, 2(6):526-32. PubMed 10457310 5. Eriksson B, Arnberg H, Lindgren PG, et al, “Neuroendocrine Pancreatic Tumours: Clinical Presentation, Biochemical and Histopathological Findings in 84 Patients,” J Intern Med, 1990, 228(2):103-13.PubMed 2168468