Vasoactive Intestinal Polypeptide (VIP), Plasma
Vasoactive intestinal polypeptide (VIP) was originally isolated from porcine small intestine and was recognized by its potent vasodilator activity. This brain/gut hormone has widespread distribution and is present in neuronal cell bodies localized in the central nervous system, digestive, respiratory, and urogenital tracts, exocrine glands, and thyroid and adrenal glands. VIP has a wide scope of biological actions. The main effects of VIP include relaxation of smooth muscle (bronchial and vascular dilation), stimulation of gastrointestinal water and electrolyte secretion, and release of pancreatic hormones.
VIP producing tumors (VIPomas) are rare; most (90%) are located in the pancreas. Watery diarrhea, hypokalemia, and achlorhydria are key symptoms.
Detection of vasoactive intestinal polypeptide producing tumors in patients with chronic diarrheal diseases
Values >75 pg/mL may indicate presence of enteropancreatic tumor causing hypersecretion of vasoactive intestinal polypeptide (VIP).
Values >200 pg/mL are strongly suggestive of VIP producing tumors (VIPoma).
VIPoma is unlikely with a 24-hour stool volume <700 mL.
This test should not be requested in patients who have recently received radioisotopes, therapeutically or diagnostically, because of potential assay interference. A recommended time period before collection cannot be made because it will depend on the isotope administered, the dose given and the clearance rate in the individual patient. Specimens will be screened for radioactivity prior to analysis. Radioactive samples received in the laboratory will be held and assayed after the radioactivity has sufficiently decayed. This will result in a test delay.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Said SI: Vasoactive intestinal peptide. J Endocrinol Invest 1986;9:191-200
2. Yaksh TL, Michener SR, Bailey JE, et al: Survey of distribution of substance P, vasoactive intestinal polypeptide, cholecystokinin, neurotensin, metenkephalin, bombesin, and PHI in the spinal cord of cat, dog, sloth, and monkey. Peptides 1988;9:357-372