Zollinger-Ellison syndrome is a condition in which one or more tumors grow in the pancreas or small intestine. The tumors, called gastrinomas, produce large amounts of the hormone gastrin. Gastrin causes the stomach to produce too much acid, which leads to peptic ulcers. High gastrin levels also can cause diarrhea, belly pain and other symptoms., Zollinger-Ellison syndrome (ZES) happens if you have a gastrinoma, a tumor in your endocrine system, which makes your body release lots of gastric acid., Zollinger-Ellison syndrome (ZES) is a disease of the gastrointestinal system. People who have ZES develop tumors known as gastrinomas in the pancreas and duodenum (the first section of the, Zollinger-Ellison syndrome (ZES) is a group of symptoms comprised of severe peptic ulcer disease, gastroesophageal reflux disease (GERD), and chronic diarrhea caused by a gastrin-secreting tumor of the duodenum or pancreas (gastrinoma triangle) that results in increased stimulation of acid-secreting cells of the stomach., Zollinger-Ellison syndrome (ZES) is a condition in which tumors called gastrinomas in the pancreas and duodenum (part of the small intestine) cause high levels of the hormone gastrin in the blood., Learn about Zollinger-Ellison syndrome, in which tumors in the pancreas or duodenum increase stomach acid, leading to peptic ulcers, acid reflux, and diarrhea..