Vasoactive Intestinal Polypeptide (VIP), Plasma

Vasoactive intestinal polypeptide (VIP) is a neurohormone produced in the central nervous system as well as in the neurons of the gastrointestinal (GI), respiratory and urogenital tracts.¹ 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.^2,3

VIP secreting tumors (VIPoma) is a rare functional neuroendocrine tumor that typically arises from pancreatic islet cells.^4-10 The VIPoma syndrome is also known as Verner-Morrison syndrome, watery diarrhea, hypokalemia, and hypochlorhydria or achlorhydria (WDHA) syndrome, and pancreatic cholera syndrome.¹ VIPomas are functional neuroendocrine tumors that secrete excessive amounts of VIP. VIPoma tumors present as sporadic, solitary pancreatic neoplasias with an estimated incidence of one in ten million individuals per year.¹¹ Approximately five percent of VIPomas are associated with multiple endocrine neoplasia type I syndrome.¹² Excessive VIP secretion produces a clinical syndrome characterized by refractory watery diarrhea, hypokalemia and achlorhydria. These symptoms, coupled with elevated plasma levels of VIP, are diagnostic. The majority of VIPomas are malignant and have already metastasized at the time of diagnosis.