Updated: 12/11/2021

Zollinger-Ellison Syndrome

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  • Snapshot
    • A 42-year-old male presents to the clinic complaining of upper abdominal pain. He reports he is under considerable stress at work and smokes a pack of cigarettes every day. The pain occurs between meals and is worse at night and often wakes him from sleep. On 1 occasion he vomited blood. Testing reveals a basal acid output (BA) of 60 mEq (normal is < 5 mEq) and a serum gastrin level of 1,000 pg/ml (normal is < 300 pg/ml).
  • Introduction
    • Clinical definition
      • syndrome characterized by the secretion of gastrin by duodenal or pancreatic neuroendocrine tumors (gastrinomas)
    • Associated conditions
      • multiple endocrine neoplasia type 1 (MEN1)
  • ETIOLOGY
    • Pathogenesis
      • excessive gastrin secretion from gastrinoma leads to high gastric acid output
        • gastrin has trophic action on gastric parietal cells and histamine-secreting enterochromaffin-like cells
      • high gastric acid secreting overwhelms the neutralizing capacity of pancreatic bicarbonate secretion, resulting in low pH of intestinal contents
        • the low pH inactivates pancreatic digestive enzymes and thus interferes with the emulsification of fat by bile acids
        • results in maldigestion and malabsorption
      • high serum gastrin concentrations inhibit the absorption of sodium and water by the small intestine
  • Epidemiology
    • Demographics
      • annual incidence is 0.5-2/million population
      • high incidence in men compared to women
    • Only 25% of gastrinomas arise in the pancreas with the majority occurring in the duodenum
  • Presentation
    • Symptoms
      • peptic ulcer disease
      • heartburn
      • weight loss
      • diarrhea
    • Physical exam
      • Abdominal tenderness
  • imaging
    • Various imaging techniques are indicated for tumor localization
      • upper endoscopy
      • contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI)
      • somatostatin receptor scintigraphy
    • Endoscopic ultrasound
      • usually indicated prior to surgical resection as it has greater sensitivity in detecting small tumors
  • Studies
    • Diagnostic testing
      • diagnostic approach
        • diagnosis is primarily based on clinical presentation (e.g., refractory peptic ulcers)
      • studies
        • fasting serum gastrin concentration and gastric pH
          • best initial test
          • serum gastrin value > 10 times the upper limit of normal (> 1,000 pg/mL) in the presence of gastric pH < 2 is diagnostic
        • secretin stimulation test
          • indicated in patients with elevated gastrin/low gastrin pH that are not diagnostic
          • differentiates gastrinomas from other causes of hypergastrinemia (e.g., antral G-cell hyperplasia)
          • patients with gastrinomas will have a dramatic rise in serum gastrin following secreting stimulation (normal gastric G cells are inhibited by secretin)
        • calcium infusion study
          • indicated in patients with strong clinical suspicion despite a negative secretin stimulation test
        • MEN1 evaluation
          • serum parathormone levels
          • ionized calcium levels
          • prolactin levels
  • Differential
    • Antral G-cell hyperplasia
      • distinguishing factors
        • poor response to secretin stimulation test
        • absence of gastrinoma on imaging
  • Treatment
    • First-line
      • medical management with proton pump inhibitors (e.g., omeprazole) and H2-receptor anatagonists (e.g., ranitidine)
      • surgical resection
        • eliminates need for antisecretory medical therapy and protects against the morbidity and mortality of metastasis
  • Complications
    • Stricture
    • Perforation
    • Metastatic gastrinoma
      • liver is the most common site
      • most common cause of morbidity and mortality

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