Zollinger‑Ellison Syndrome (Acid Hypersecretion)

What is Zollinger‑Ellison syndrome (acid hypersecretion)?

Zollinger‑Ellison syndrome (ZES) is a rare neuroendocrine disorder in which one or more tumors, called gastrinomas, develop in the pancreas or duodenum. These tumors secrete excessive amounts of the hormone gastrin, which stimulates the stomach lining to produce far more gastric acid than normal. The resulting acid hypersecretion leads to severe peptic ulcers, chronic diarrhea, and malabsorption.

Although ZES accounts for less than 1 % of all gastric ulcer disease, it is clinically important because the ulcers are often refractory to standard therapy and can be life‑threatening if not recognized early [Mayo Clinic].

Common Causes

Zollinger‑Ellison syndrome is most often caused by a gastrinoma, but several underlying conditions can increase the risk of developing these tumors or mimic the syndrome’s presentation:

• Spontaneous (sporadic) gastrinomas: Occur without any identifiable genetic syndrome (≈70 % of cases).
• Multiple endocrine neoplasia type 1 (MEN‑1): An inherited disorder that predisposes to pancreatic tumors, including gastrinomas.
• Multiple endocrine neoplasia type 4 (MEN‑4): Rare, but also linked to gastrinoma development.
• Familial gastrinoma: Autosomal‑dominant inheritance of gastrin‑producing tumors without other MEN features.
• Chronic H. pylori infection: Can cause elevated gastrin levels and, in rare cases, trigger hypersecretion.
• Chronic atrophic gastritis: Leads to loss of acid‑producing cells and compensatory hypergastrinemia.
• Proton‑pump inhibitor (PPI) overuse: Long‑term high‑dose PPI therapy can raise gastrin levels, though usually not to ZES levels.
• Gastric outlet obstruction: Causes stasis and secondary hypergastrinemia.
• Renal failure: Impaired clearance of gastrin may augment circulating levels.
• Rare neuroendocrine tumors of the bronchus: Ectopic gastrin production (very uncommon).

Associated Symptoms

The hallmark of ZES is persistent acid hypersecretion. Typical clinical features include:

• Recurrent or refractory peptic ulcers (often multiple, located beyond the duodenum, e.g., in the jejunum).
• Severe, watery diarrhea (up to 5–10 L/day in extreme cases).
• Abdominal pain or burning sensation.
• Weight loss and malnutrition due to malabsorption of fat‑soluble vitamins.
• Nausea and vomiting, sometimes with blood (hematemesis).
• Epigastric fullness or early satiety.
• Fatigue, anemia, or iron deficiency from chronic blood loss.
• Occasional biliary colic if duodenal ulcers cause obstruction.

When to See a Doctor

Because ZES can mimic common gastrointestinal disorders, early medical evaluation is crucial when any of the following occur:

• Persistent abdominal pain that does not improve with over‑the‑counter antacids.
• Ulcers that recur within weeks of successful treatment.
• Diarrhea that is chronic (>2 weeks), watery, and does not respond to standard anti‑diarrheal medication.
• Unexplained weight loss or signs of malnutrition.
• Vomiting of blood or black, tarry stools (melena).
• Family history of MEN‑1, MEN‑4, or other endocrine tumors.
• Symptoms that interfere with daily activities or cause severe fatigue.

Diagnosis

Diagnosing ZES involves confirming both hypergastrinemia and the presence of a gastrinoma. The typical work‑up includes:

Laboratory Tests

• Fasting serum gastrin level: Values >1000 pg/mL are highly suggestive; modest elevations require provocative testing.
• Secretin stimulation test: Intravenous secretin normally suppresses gastrin; a paradoxical rise (>120 pg/mL) supports ZES.
• Basic metabolic panel (calcium, magnesium) to assess for MEN‑1‑related hyperparathyroidism.
• Complete blood count (CBC) to detect anemia or infection.
• Fecal fat or stool elastase if malabsorption is suspected.

Imaging Studies

• Endoscopic ultrasound (EUS): Sensitive for small pancreatic or duodenal lesions.
• Multiphasic contrast‑enhanced CT or MRI: Maps tumor size, location, and metastasis.
• Somatostatin receptor scintigraphy (Octreoscan) or ^68Ga‑DOTATATE PET/CT: Detects neuroendocrine tumors expressing somatostatin receptors.
• Upper gastrointestinal endoscopy: Direct visualization of ulcers and biopsies to rule out malignancy.

Pathology

If a lesion is surgically removed, histopathology confirms a well‑differentiated neuroendocrine tumor with immunohistochemical staining for gastrin.

Treatment Options

Therapy aims to control acid hypersecretion, manage symptoms, and eradicate or reduce tumor burden.

Medical Management

• Proton‑pump inhibitors (PPIs): High‑dose omeprazole, esomeprazole, or lansoprazole are first‑line; they normalize gastric pH and heal ulcers in >90 % of patients [Cleveland Clinic].
• Histamine‑2 receptor antagonists (H2RAs): Often used as adjuncts, though less effective than PPIs.
• Antidiarrheal agents: Loperamide or diphenoxylate‑atropine for symptom control.
• Somatostatin analogues (octreotide, lanreotide): Decrease gastrin secretion and may shrink tumors, especially in metastatic disease.
• Chemotherapy or targeted therapy: For unresectable or progressive neuroendocrine tumors (e.g., everolimus, sunitinib).

Surgical Intervention

When feasible, surgery offers the best chance for cure:

• Enucleation or limited pancreaticoduodenectomy: For localized gastrinomas.
• Debulking surgery: Reduces tumor load when complete resection is impossible.
• Liver-directed therapies: Radiofrequency ablation or hepatic artery embolization for liver metastases.

Home and Lifestyle Measures

• Adhere strictly to prescribed PPI dosing; do not stop abruptly without medical advice.
• Stay hydrated—especially important if diarrhea is frequent.
• Consume a balanced diet rich in protein and low in simple carbohydrates; consider small, frequent meals.
• Supplement fat‑soluble vitamins (A, D, E, K) if malabsorption is documented.
• Avoid alcohol, tobacco, and NSAIDs, which can worsen ulcer disease.

Prevention Tips

Because most gastrinomas are sporadic, primary prevention is limited. However, the following strategies can reduce risk or detect disease early:

• Genetic counseling and periodic screening for individuals with a family history of MEN‑1 or MEN‑4.
• Routine monitoring of gastrin levels in patients with chronic PPI use who develop new gastrointestinal symptoms.
• Eradication of H. pylori infection to avoid secondary hypergastrinemia.
• Regular follow‑up with an endocrinologist or gastroenterologist for known pancreatic neuroendocrine tumors.
• Maintain a healthy weight and avoid excessive alcohol, which can exacerbate gastric mucosal injury.

Emergency Warning Signs

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© 2026 HealthInfoHub. Content reviewed by board‑certified gastroenterologists. Sources: Mayo Clinic, Cleveland Clinic, NIH National Institute of Diabetes and Digestive and Kidney Diseases, CDC, WHO, peer‑reviewed gastroenterology journals.