Zollinger-Ellison syndrome (ZES) is caused by a gastrin-producing tumor called a gastrinoma, which results in gastric acid hypersecretion. Gastrin stimulates the parietal cell to secrete acid directly and indirectly by releasing histamine from enterochromaffin-like (ECL) cells, and induces hyperplasia of parietal and ECL cells. ZES should be suspected in patients with severe erosive or ulcerative esophagitis, multiple peptic ulcers, peptic ulcers in unusual locations, refractory peptic ulcers, complicated peptic ulcers, peptic ulcers associated with diarrhea, and a family history of multiple endocrine neoplasia type 1 (MEN-1) or any of the endocrinopathies associated with MEN-1. The initial diagnostic test for ZES should be a fasting serum gastrin level when antisecretory medications are discontinued. If the gastrin level is elevated, gastric acidity should be assessed through pH or gastric analysis. It should be noted that hypochlorhydria causes feedback stimulation of antral gastrin secretion. In suspected cases of ZES with mild hypergastrinemia, the secretin stimulation test may be useful. Initial treatment for ZES should be oral high-dose proton pump inhibitors. If parenteral therapy is needed, intermittent bolus injection of pantoprazole is recommended. Total gastrectomy and antisecretory surgery is rarely required. Somatostatin receptor scintigraphy (SRS) is the initial localization study of choice. Endoscopic ultrasound (EUS) may have a similar sensitivity for identifying primary tumors. A combination of SRS and EUS detects greater than 90% of gastrinomas. In patients without metastasis and without MEN-1, surgical cure is possible in 30%. It has been suggested that patients with gastrinomas larger than 2.5 cm, irrespective of whether they have MEN-1, should undergo surgical resection in an effort to decrease the risk for metastasis.
