Zollinger-Ellison syndrome in a patient with normal screening gastrin level

A 59-year-old female presented with multifocal peptic ulcer disease and diarrhea. A fasting serum gastrin level obtained while the patient was receiving no antacid therapy was normal. A secretin stimulation test was positive. A small gastrinoma was found in the anterior duodenal wall at exploratory laparotomy. Normal fasting gastrin levels do occur in patients with overt Zollinger-Ellison syndrome and should not deter further investigation if clinical suspicion of this syndrome is high.