Zollinger‑Ellison gastrinoma (type I) - Symptoms, Causes, Treatment & Prevention

Overview

Zollinger‑Ellison syndrome (ZES) is a rare disorder caused by one or more gastrin‑producing tumors called gastrinomas. When the gastrinoma originates in the pancreas or duodenum and is confined to the gastrointestinal (GI) tract, it is classified as type I (also called “gastrinoma‑type”). These tumors secrete excessive amounts of the hormone gastrin, which stimulates the stomach lining to produce large volumes of gastric acid.

Key points:

• Incidence: Approximately 0.5–2 cases per million people per year worldwide.¹
• Typical age of diagnosis: 30–60 years, but cases in adolescents and the elderly are reported.
• Gender: Slight male predominance (about 55 % men).
• Most gastrinomas (≈90 %) are sporadic; ~10 % occur as part of the inherited MEN‑1 (multiple endocrine neoplasia type 1) syndrome.

Symptoms

Excess gastric acid leads to a spectrum of GI and systemic complaints. Symptoms can be intermittent early on, becoming more severe as the tumor grows or metastasizes.

Gastro‑intestinal

• Refractory peptic ulcer disease: Ulcers that fail to heal with standard therapy, often multiple and located distal to the duodenum.
• Epigastric pain: Burning or gnawing pain that may improve after meals (due to buffering) or worsen with fasting.
• Diarrhea: Occurs in >70 % of patients; the acid inactivates pancreatic enzymes and damages the intestinal mucosa, causing malabsorption.
• Steatorrhea (fatty stools): Result of fat malabsorption; stools are bulky, foul‑smelling, and float.
• Nausea & vomiting: Particularly after large meals or alcohol.
• Gastro‑esophageal reflux disease (GERD): Acid overload overwhelms the lower esophageal sphincter.

Systemic / Extra‑intestinal

• Weight loss: Due to malabsorption and chronic diarrhea.
• Fatigue & anemia: Chronic GI bleeding from ulcers or malabsorption of iron and B12.
• Osteopenia/osteoporosis: Long‑standing acid‑related calcium loss.
• Skin flushing or pellagra‑like rash: Rare, linked to niacin deficiency.

Causes and Risk Factors

Zollinger‑Ellison gastrinoma type I is primarily the result of a single cell mutation that leads to uncontrolled gastrin secretion.

• Genetic mutations: Sporadic gastrinomas often harbor alterations in the MEN1 gene, CDKN1B, and APC. Inherited MEN‑1 syndrome (mutations in MEN1) raises the lifetime risk of gastrinoma to 20‑30 %.
• Family history: Having a first‑degree relative with MEN‑1 or ZES increases risk.
• Age & sex: Risk rises after age 30; males are slightly more affected.
• Environmental factors: No clear link to diet, smoking, or alcohol, unlike typical peptic ulcer disease.

Diagnosis

Because symptoms overlap with common ulcer disease, a high index of suspicion is needed, especially when ulcers are refractory or there is unexplained diarrhea.

Step‑by‑step diagnostic approach

1. Clinical evaluation: Detailed history, focused physical exam, and review of prior ulcer treatments.
2. Laboratory tests:
   • Fasting serum gastrin level – a value > 1,000 pg/mL (or > 10× upper limit) strongly suggests ZES.
   • Secretin stimulation test – paradoxical rise in gastrin after IV secretin (≥ 120 pg/mL increase) is diagnostic in equivocal cases.
   • Baseline gastric pH – a pH < 2 confirms acid hypersecretion.
   • Routine labs: CBC, iron studies, calcium, vitamin B12, and liver function to assess complications.
3. Imaging studies to locate the tumor:
   • Multiphasic contrast CT scan of the abdomen and pelvis (sensitivity ~70‑80 %).
   • Magnetic Resonance Imaging (MRI) with gadolinium – useful for liver metastases.
   • Somatostatin receptor scintigraphy (Octreoscan) or ^68Ga‑DOTATATE PET/CT – highest sensitivity (≈ 90 %) for small gastrinomas.
   • Endoscopic ultrasound (EUS) – excellent for lesions < 2 cm, especially in the duodenum.
4. Endoscopic evaluation: Upper endoscopy (EGD) reveals ulcerations, esophagitis, and allows biopsy to exclude malignancy.
5. Genetic testing: Recommended for patients < 40 years old, those with a familial pattern, or evidence of MEN‑1 (parathyroid or pituitary lesions).

Treatment Options

Therapy aims to control acid hypersecretion, eradicate or control the tumor, and manage complications.

Medical Management

• Proton pump inhibitors (PPIs): High‑dose (e.g., omeprazole 80 mg daily or equivalent) are first‑line; they normalize gastric pH and heal ulcers in > 90 % of patients.²
• H2‑receptor antagonists: Used when PPIs are contraindicated or as adjunct therapy.
• Octreotide (somatostatin analog): Reduces gastrin secretion; useful for patients with metastatic disease or those intolerant to PPIs.
• Supportive supplements: Calcium, vitamin D, and iron replacement as needed.

Surgical Options

• Localized tumor resection: Enucleation or limited pancreaticoduodenectomy (Whipple) when the tumor is confined and resectable. Curative intent in 60‑70 % of sporadic cases.
• Debulking surgery: Reduces tumor burden in metastatic disease; often combined with medical therapy.
• Radiofrequency ablation or hepatic artery embolization: Target liver metastases when surgery is not feasible.

Targeted / Systemic Therapies

• Everolimus or sunitinib: Used for progressive, unresectable neuroendocrine tumors.
• Peptide receptor radionuclide therapy (PRRT): ^177Lu‑DOTATATE for somatostatin‑receptor positive disease; improves progression‑free survival.

Lifestyle & Dietary Measures

• Avoid foods that aggravate acid (spicy foods, caffeine, alcohol, nicotine).
• Eat small, frequent meals; include complex carbohydrates to buffer acid.
• Maintain adequate hydration, especially if diarrhea is prominent.
• Limit high‑fat meals that can worsen steatorrhea.

Living with Zollinger‑Ellison Gastrinoma (type I)

Long‑term management focuses on quality of life, adherence to medication, and monitoring for disease progression.

• Medication adherence: Take PPIs exactly as prescribed; never skip doses.
• Regular follow‑up: Serum gastrin every 6–12 months, imaging annually or sooner if symptoms change.
• Nutritional support: Work with a dietitian to manage malabsorption, supplement fat‑soluble vitamins (A, D, E, K), and correct mineral deficiencies.
• Monitor for MEN‑1 manifestations: Annual calcium, PTH, and prolactin levels; breast, pituitary, and parathyroid screening as indicated.
• Psychosocial care: Chronic disease can cause anxiety or depression; counseling or support groups are beneficial.

Prevention

Because most gastrinomas are sporadic and genetic, primary prevention is limited. However, risk reduction strategies include:

• Genetic counseling for families with MEN‑1.
• Early screening of at‑risk relatives (serum gastrin, imaging) per endocrinology guidelines.
• Prompt treatment of H. pylori infection and avoidance of unnecessary chronic NSAID use – while they do not cause gastrinomas, they can exacerbate ulcer disease.

Complications

If untreated or inadequately controlled, ZES can lead to serious health problems.

• Refractory or perforated peptic ulcers – risk of peritonitis and sepsis.
• Gastrointestinal bleeding – anemia, need for transfusion.
• Severe malnutrition – weight loss > 15 % body weight, electrolyte disturbances.
• Metastatic disease: Approximately 25‑35 % of gastrinomas spread to the liver or regional lymph nodes.
• Osteoporotic fractures – chronic acid loss of calcium.
• Reduced life expectancy: Median survival > 10 years with modern therapy, but < 5 years in uncontrolled metastatic disease.

When to Seek Emergency Care

Early recognition and treatment of these emergencies can be lifesaving.

References

1. Mayo Clinic. Zollinger‑Ellison syndrome. https://www.mayoclinic.org. Accessed May 2024.
2. World Health Organization. WHO Classification of Tumours of the Digestive System. 5th ed.; 2020.
3. Cleveland Clinic. Gastrinoma (Zollinger‑Ellison Syndrome). https://my.clevelandclinic.org. Accessed May 2024.
4. National Institutes of Health. National Cancer Institute. Neuroendocrine Tumors Treatment (PDQ). https://www.cancer.gov. Updated 2023.
5. European Neuroendocrine Tumor Society (ENETS) Guidelines for Gastrinoma Management. Neuroendocrinology, 2022;112(3):215‑230.