Mild chronic watery diarrhea-hypokalemia syndrome associated with pancreatic islet cell hyperplasia. Elevated plasma and tissue levels of gastric inhibitory polypeptide and successful management with nicotinic acid.

A 46 year old woman is described who had a 13 half year history of watery diarrhea associated with hypokalemia and hypochlorhydria. The diarrhea was secretory as measured by triple lumen tube perfusion and was associated with an increased concentration of fasting plasma immunoreactive gastric inhibitory polypeptide (GIP) of 750 pg/ml which was stimulated to 4,000 pg/ml after a standard meal. The diarrhea decreased after partial pancreatectomy. Diffuse pancreatic islet cell hyperplasia was present and, although GIP was unmeasureable in the pancreas of normal subjects, it was at least 83 ng/g wet weight in this patient. Postoperatively, the patient's diarrhea responded dramatically to the oral administration of nicotinic acid.