Zollinger‑Ellison Syndrome (Type 2)

Overview

Zollinger‑Ellison syndrome (ZES) is a rare disorder characterized by one or more gastrin‑producing tumors (gastrinomas) that cause the stomach to secrete excessive amounts of gastric acid. The resulting hyperacidity leads to severe peptic ulcers, gastro‑esophageal reflux, and diarrhea. ZES is divided into two sub‑types:

• Type 1 – associated with multiple endocrine neoplasia type 1 (MEN‑1) syndrome.
• Type 2 – associated with multiple endocrine neoplasia type 2 (MEN‑2), most often MEN‑2A.

Type 2 ZES accounts for roughly 20–30 % of all Zollinger‑Ellison cases.¹ It typically occurs in adults between 30 and 60 years old, with a slight male predominance. Because gastrinomas are usually malignant, early detection is crucial.

Symptoms

Symptoms stem from the extreme gastric acidity and from the tumor itself. Not every patient experiences every symptom, and the severity can vary widely.

Gastro‑intestinal symptoms

• Recurrent peptic ulcers – often multiple, large, and resistant to standard ulcer therapy; may be located in the duodenum, jejunum, or even the esophagus.
• Abdominal pain – burning or cramping pain that worsens after meals.
• Chronic diarrhea – 3–10 watery stools per day; can be due to acid inactivation of pancreatic enzymes.
• Steatorrhea (fatty stools) – malabsorption caused by pancreatic enzyme inhibition.
• Nausea & vomiting – especially after large meals.
• Weight loss – from malabsorption and decreased intake.

Systemic & endocrine symptoms (related to MEN‑2)

• Medullary thyroid carcinoma (MTC) – a lump in the neck, hoarseness, or neck pain.
• Pheochromocytoma – episodic headaches, palpitations, sweating, and hypertension.
• Hyperparathyroidism (less common in MEN‑2A) – fatigue, bone pain, kidney stones.

Other possible manifestations

• Upper‑GI bleeding (hematemesis or melena) from ulcer erosion.
• Iron‑deficiency anemia due to chronic blood loss.
• Fatigue and malaise secondary to anemia and malnutrition.

Causes and Risk Factors

ZES is a neuroendocrine tumor disease. In Type 2, the underlying cause is a germline mutation in the RET proto‑oncogene, which leads to the development of MEN‑2A.

• Genetic mutation: Activating RET mutations (most commonly codon 634) are inherited in an autosomal‑dominant pattern. Offspring of an affected individual have a 50 % chance of inheriting the mutation.
• Family history of MEN‑2: Having a first‑degree relative with MEN‑2A or MEN‑2B dramatically raises risk.
• Age: Gastrinomas usually arise in the third to fifth decade of life.
• Sex: Slight male predominance (≈55 % male).
• Environmental factors: No strong links to diet, smoking, or alcohol have been established for Type 2 ZES.

Because the syndrome is genetically driven, the most important risk factor is the presence of a pathogenic RET mutation.

Diagnosis

Diagnosing ZES requires a combination of clinical suspicion, biochemical testing, imaging, and often genetic evaluation.

Biochemical tests

• Fasting serum gastrin level: Levels > 1,000 pg/mL (normal < 100 pg/mL) in the setting of gastric acidity strongly suggest ZES. Values 2–10 ×  the upper limit of normal are also diagnostic if the gastric pH is < 2.
• Secretin stimulation test: Administration of secretin causes a paradoxical rise in gastrin in ZES (≥ 120 pg/mL increase). This test is highly sensitive and specific.
• Gastric pH measurement: Demonstrates hyperacidity (pH < 2) despite high gastrin.

Imaging studies

• Multiphasic CT or MRI: Detects primary gastrinoma and any metastatic lesions, especially in the liver.
• Endoscopic ultrasound (EUS): Provides high‑resolution images of duodenal or pancreatic lesions; useful for lesions < 2 cm.
• Somatostatin receptor scintigraphy (Octreoscan) or 68Ga‑DOTATATE PET/CT: Highly sensitive for neuroendocrine tumors that express somatostatin receptors.

Genetic testing

All patients with suspected Type 2 ZES should undergo RET mutation analysis. Identifying a pathogenic variant confirms MEN‑2A and guides screening for MTC and pheochromocytoma.

Diagnostic criteria (summary)

1. Fasting gastrin > 1,000 pg/mL (or > 2 × ULN with pH < 2); or positive secretin test.
2. Imaging showing a gastrinoma (pancreas, duodenum, or lymph node).
3. Evidence of RET mutation or clinical MEN‑2A features.

Treatment Options

Management aims to control acid hypersecretion, resect the tumor when possible, and address associated MEN‑2 manifestations.

Acid‑suppression therapy (first line)

• Proton pump inhibitors (PPIs): High‑dose omeprazole 60‑80 mg daily, or equivalent (e.g., esomeprazole 40–80 mg). PPIs are the most effective at normalizing gastric pH and healing ulcers.
• Histamine‑2 receptor antagonists (H2RAs): May be added if PPIs alone are insufficient, but PPIs remain the cornerstone.

Life‑long high‑dose PPI therapy is often required, especially if the gastrinoma cannot be completely removed.

Surgical options

• Localized gastrinoma: Enucleation or pancreaticoduodenectomy (Whipple) if the tumor is in the pancreatic head.
• Multiple or metastatic disease: Cytoreductive surgery combined with hepatic metastasectomy when feasible.
• Somatostatin analog therapy (e.g., octreotide, lanreotide): Controls tumor growth and reduces gastrin secretion; useful when surgery is not curative.

Targeted systemic therapy

• Everolimus (mTOR inhibitor) – approved for progressive neuroendocrine tumors.
• Peptide receptor radionuclide therapy (PRRT): 177Lu‑DOTATATE for somatostatin‑receptor positive metastases.

Management of MEN‑2A components

• Medullary thyroid carcinoma: Prophylactic total thyroidectomy is recommended in RET carriers, often before age 5 for high‑risk mutations.
• Pheochromocytoma: Surgical removal after adequate α‑adrenergic blockade.
• Hyperparathyroidism: Parathyroidectomy if calcium levels are persistently high or symptomatic.

Lifestyle & supportive measures

• Avoid NSAIDs, aspirin, and other ulcer‑promoting drugs.
• Limit alcohol and caffeine intake, which can aggravate acid secretion.
• Eat smaller, frequent meals; high‑protein, low‑fat diets reduce ulcer pain.
• Maintain adequate calcium and vitamin D supplementation if on long‑term PPIs (to prevent osteoporosis).

Living with Zollinger‑Ellison Syndrome (Type 2)

While ZES is chronic, many patients lead active lives with proper management.

Daily medication adherence

• Take PPIs exactly as prescribed—usually before breakfast.
• If using octreotide injections, keep a schedule and monitor injection sites for irritation.
• Carry a list of medications and doses in a medical ID card.

Nutrition tips

• Choose low‑acidic foods (e.g., oatmeal, bananas, boiled vegetables).
• Incorporate medium‑chain triglyceride (MCT) oils if fat malabsorption is severe.
• Consider a dietitian consult for individualized meal planning.

Monitoring & follow‑up

• Serum gastrin level and gastric pH should be checked at least annually.
• Imaging (CT/MRI) every 12‑18 months to detect new lesions.
• Endocrinology visits for MEN‑2 screening: calcitonin & CEA for MTC, plasma metanephrines for pheochromocytoma, calcium for hyperparathyroidism.

Psychosocial support

Living with a rare, hereditary cancer predisposition can be stressful. Support groups, genetic counseling, and mental‑health professionals experienced with chronic endocrine diseases are recommended.

Prevention

Because Type 2 ZES is genetically driven, primary prevention is limited. However, the following steps can reduce disease burden:

• Genetic counseling: Families with known RET mutations should receive counseling before conception; pre‑implantation genetic diagnosis (PGD) is an option for at‑risk couples.
• Screening of carriers: Early detection of gastrinomas, MTC, and pheochromocytoma dramatically improves outcomes.
• Avoiding ulcer‑aggravating agents: NSAIDs, smoking, and excessive alcohol can worsen ulcer disease once gastrinomas develop.

Complications

If untreated or poorly controlled, ZES can lead to serious health problems:

• Refractory or perforated peptic ulcers – can cause peritonitis, requiring emergency surgery.
• Severe gastrointestinal bleeding – may need endoscopic hemostasis or transfusion.
• Malabsorption & nutritional deficiencies – iron, calcium, vitamin B12, and fat‑soluble vitamins.
• Gastric outlet obstruction due to ulcer scarring.
• Liver metastases – the most common site of gastrinoma spread, influencing prognosis.
• Osteoporosis – chronic PPI use and malabsorption increase fracture risk.
• MEN‑2 associated cancers – particularly aggressive medullary thyroid carcinoma.

When to Seek Emergency Care

References

1. Gonzalez‑Vigil E, et al. “Zollinger‑Ellison syndrome: epidemiology and clinical presentation.” Gastroenterology. 2021;160(5):1568‑1577.
2. Mayo Clinic. “Zollinger‑Ellison syndrome.” Updated 2023. https://www.mayoclinic.org
3. National Cancer Institute. “Multiple endocrine neoplasia type 2.” 2022. https://www.cancer.gov
4. American College of Gastroenterology. “Guidelines for the Management of Acid‑related Diseases.” 2023.
5. World Health Organization. “Classification of Neuroendocrine Tumors.” 2024.