Vasoative intestinal peptide and the watery diarrhea syndrome.

A sensitive and specific radioimmunoassay for the detection of vasoactive intestinal peptide has been used to study patients with the watery diarrhea syndrome. In eleven patients the syndrome was associated with tumors, and plasma levels of vasoactive intestinal peptide were elevated. VIP levels returned towards normal in five treated patients coincident with amelioration of symptoms. Normal values were obtained in patinets with chronic pancreatitis, sprue, medullary carcinoma, Zollinger-Ellison Syndrome and laxative abuse. In six other patients with indistinguishable syndrome and no findings of tumor at laparotomy and autopsy, vasoactive intestinal peptide levels were normal. The results suggest that VIP may be the causative agent in patients with the watery diarrhea syndrome and tumors, but that an indistinguishable syndrome exists for which VIP is not the cause.