A 45-year-old man presents to the clinic with a history of burning midepigastric abdominal pain over the past year. He reports that he has been treated with proton pump inhibitors (PPIs) and H2 blockers, but his symptoms have persisted. He also mentions experiencing diarrhea and weight loss during this time. He denies seeing blood in the stools. Vital signs are within normal limits. On physical examination, he has epigastric tenderness to palpation. An upper endoscopy reveals an ulcer in the proximal duodenum and in the distal duodenum.
Which of the following is the most appropriate next step in the evaluation of this patient?
C) Fasting serum gastrin level
This patient has multiple ulcers, including the distal duodenum which is not typical. These ulcers have been resistant to appropriate therapy and are accompanied by diarrhea and weight loss. Zollinger-Ellison syndrome (ZES) is a gastrinoma that causes acid hypersecretion and peptic ulcer disease because gastrin stimulates acid secretion. Peptic ulcer disease, heartburn, diarrhea, and weight loss are the most common symptoms. Peptic ulcers in ZES are often multiple, resistant to therapy, and found in atypical locations such as the distal duodenum. Diagnosis is made with an elevated fasting serum gastrin level or a secretin stimulation test.
Answer choice A: Abdominal ultrasound, is incorrect. An abdominal ultrasound is not the most appropriate next step for diagnosing Zollinger-Ellison syndrome. It is not useful for detecting gastrinomas or assessing serum gastrin levels.
Answer choice B: Colonoscopy, is incorrect. A colonoscopy is not indicated in the evaluation of peptic ulcers and would not help in diagnosing Zollinger-Ellison syndrome.
Answer choice D: Helicobacter pylori stool antigen test, is incorrect. While H. pylori infection can cause peptic ulcers, the presence of multiple, therapy-resistant ulcers in atypical locations suggests Zollinger-Ellison syndrome, making the fasting serum gastrin level the more appropriate test.
Answer choice E: Serum amylase and lipase levels, is incorrect. Serum amylase and lipase levels are used to evaluate pancreatitis and are not relevant to the diagnosis of Zollinger-Ellison syndrome.
Key Learning Point
Zollinger-Ellison syndrome is a gastrinoma that causes acid hypersecretion and peptic ulcer disease because gastrin stimulates acid secretion. Peptic ulcers are often multiple, resistant to therapy, and found in atypical locations such as the distal duodenum. Diagnosis is made with an elevated fasting serum gastrin level or a secretin stimulation test.
