Zollinger‑Ellison Associated Gastrinoma Syndrome
Overview
Zollinger‑Ellison syndrome (ZES) is a rare disorder caused by one or more gastrin‑secreting tumors called gastrinomas. These tumors are most often found in the pancreas or duodenum and lead to excessive gastric acid production. The resulting hyperacidity can cause recurrent peptic ulcers, diarrhea, and malabsorption. When the gastrinoma is part of the hereditary condition multiple endocrine neoplasia type 1 (MEN 1), it is referred to as Zollinger‑Ellison associated gastrinoma syndrome.
Who it affects: ZES can develop at any age but is most commonly diagnosed in people between 30 and 60 years old. Men and women are affected equally. Approximately 25‑30 % of patients have an underlying MEN 1 mutation, while the remaining cases are sporadic.1
Prevalence: Gastrinomas are rare, with an estimated incidence of 0.5–2 cases per million people per year. Because many tumors are small and asymptomatic, the true prevalence may be higher.2
Symptoms
Symptoms result from the combination of excessive acid and the mass effect of the tumor.
- Recurrent peptic ulcers – ulcers appear in the duodenum or jejunum and often resist standard ulcer therapy.
- Abdominal pain – crampy or burning pain that may improve after meals (ulcer pain) or worsen (acid reflux).
- Diarrhea – watery, often nocturnal, caused by acid inactivating pancreatic enzymes and damaging the intestinal mucosa.
- Steatorrhea (fatty stools) – malabsorption of fats due to pancreatic enzyme inactivation.
- Weight loss – secondary to malabsorption and chronic diarrhea.
- Gastroesophageal reflux disease (GERD) – heartburn, sour taste, regurgitation.
- Nausea and vomiting – especially after large meals.
- Gastrointestinal bleeding – melena or hematemesis from ulcer erosion.
- Signs of MEN 1 – hyperparathyroidism (kidney stones, bone pain) or pituitary tumors (headaches, vision changes) may coexist.
Causes and Risk Factors
Primary cause
Zollinger‑Ellison syndrome arises from a neuroendocrine tumor that secretes gastrin. The overproduction of gastrin stimulates the parietal cells of the stomach to produce large volumes of hydrochloric acid.
Genetic factors
- MEN 1 mutation – Autosomal‑dominant inheritance of a mutation in the MEN1 tumor suppressor gene. Up to 30 % of ZES patients have MEN 1.3
- Family history – First‑degree relatives of a person with MEN 1 have a 50 % chance of inheriting the mutation.
Other risk factors
- Age 30‑60 (peak incidence).
- Chronic gastrin‑stimulating conditions (e.g., prolonged use of proton‑pump inhibitors) do **not** cause ZES but may mask symptoms, leading to delayed diagnosis.
- Previous gastric surgery – rare cases of “gastrinoma‑type” hypergastrinemia after gastric bypass have been reported, but this is not a true cause.
Diagnosis
A combination of clinical suspicion, biochemical testing, imaging, and sometimes endoscopic evaluation is required.
1. Biochemical tests
- Fasting serum gastrin level – Levels > 1,000 pg/mL (reference < 100 pg/mL) are highly suggestive. Even modest elevations (≥ 150 pg/mL) in the presence of low gastric pH (< 2) support the diagnosis.4
- Secretin stimulation test – Intravenous secretin normally suppresses gastrin; in gastrinomas it paradoxically raises gastrin > 120 pg/mL after administration.
- Gastric pH measurement – A pH < 2 confirms hyperacidity.
2. Imaging studies
- Somatostatin receptor scintigraphy (Octreoscan) or ^68Ga‑DOTATATE PET/CT – Highly sensitive for locating neuroendocrine tumors, especially small duodenal lesions.
- CT or MRI of the abdomen – Detects larger tumors, liver metastases, and regional lymphadenopathy.
- EUS (endoscopic ultrasound) – Excellent for identifying sub‑centimeter duodenal gastrinomas.
3. Endoscopic evaluation
Upper endoscopy (EGD) identifies ulcer disease, allows biopsy of suspicious lesions, and can directly visualize the tumor in some cases.
4. Genetic testing
Patients with a personal or family history suggestive of MEN 1 should undergo testing for MEN1 mutations. Results guide surveillance for other endocrine tumors.
Treatment Options
Therapy is aimed at two goals: control gastric acid hypersecretion and eradicate or control the tumor.
Acid‑suppression therapy (first line)
- Proton‑pump inhibitors (PPIs) – High‑dose omeprazole, esomeprazole, or pantoprazole (typically 60–120 mg/day) are the most effective. Doses may be higher than standard ulcer therapy.
- H2‑receptor antagonists – Can be added if PPIs alone are insufficient, though they are less potent.
Acid control is usually achieved within days, markedly improving ulcer healing and diarrhea.
Surgical management
Curative surgery is possible in 60‑80 % of sporadic gastrinomas that are localized.
- Enucleation – Removal of a small, well‑encapsulated tumor.
- Pancreaticoduodenectomy (Whipple procedure) – Considered for larger or multifocal pancreatic lesions.
- Distal pancreatectomy with splenectomy – For tumors in the body or tail.
In MEN 1 patients, tumors are often multiple; surgery is reserved for symptomatic or rapidly growing lesions because complete eradication is difficult.5
Medical therapy for tumor control
- Somatostatin analogues (octreotide, lanreotide) – Inhibit gastrin release and can stabilize tumor growth.
- Targeted therapy (everolimus, sunitinib) – Approved for progressive, unresectable gastro‑intestinal neuroendocrine tumors.
- Chemotherapy – Rarely used; reserved for high‑grade neuroendocrine carcinomas.
- Peptide receptor radionuclide therapy (PRRT) – ^177Lu‑DOTATATE delivers radiation directly to somatostatin‑receptor‑positive tumors.
Liver metastasis management
- Hepatic resection or radiofrequency ablation for limited disease.
- Trans‑arterial embolization (TAE) or chemo‑embolization (TACE) for diffuse hepatic involvement.
Lifestyle and supportive measures
- Avoid non‑steroidal anti‑inflammatory drugs (NSAIDs) and aspirin, which exacerbate ulcer formation.
- Eat small, frequent meals low in fat to reduce acid‑stimulating stimulus.
- Stay hydrated; replace electrolytes if chronic diarrhea is present.
Living with Zollinger‑Ellison Associated Gastrinoma Syndrome
Medication adherence
PPIs must be taken exactly as prescribed, usually 2–3 times daily for the first few weeks, then titrated to the lowest effective dose. Missing doses can rapidly return symptoms.
Monitoring
- Serum gastrin and gastric pH every 6–12 months while on therapy.
- Annual imaging (CT/MRI or somatostatin receptor PET) to detect tumor growth or metastasis.
- For MEN 1 patients, routine screening of calcium, parathyroid hormone, and pituitary function.
Dietary tips
- Limit caffeine, alcohol, and spicy foods that stimulate acid production.
- Increase intake of complex carbohydrates and lean protein.
- Consider a low‑fat diet if steatorrhea is prominent; pancreatic enzyme supplements may be required.
Managing diarrhea
In addition to acid suppression, antidiarrheal agents (loperamide) and pancreatic enzyme replacements (e.g., pancrelipase) can improve stool consistency.
Psychosocial support
Living with a chronic, rare disease can be stressful. Support groups (e.g., GUT‑NET, Neuroendocrine Tumor Patient Foundation) and counseling are valuable resources.
Prevention
Because gastrinomas are primarily sporadic or genetically driven, true primary prevention is limited.
- Genetic counseling – Families with MEN 1 should receive counseling and consider cascade testing for at‑risk relatives.
- Avoid chronic acid‑stimulating medications – Long‑term, high‑dose PPI use without indication may mask early symptoms and delay diagnosis.
- Regular health surveillance – For known MEN 1 carriers, annual biochemical and imaging evaluations can detect gastrinomas at an early, more treatable stage.
Complications
If untreated or poorly managed, Zollinger‑Ellison associated gastrinoma syndrome can lead to:
- Refractory peptic ulcers – Can perforate, bleed, or cause obstruction.
- Upper gastrointestinal bleeding – May require transfusion or emergent endoscopy.
- Gastro‑intestinal strictures – From chronic ulcer scarring.
- Malnutrition – Due to chronic diarrhea, steatorrhea, and acid‑induced nutrient loss.
- Kidney stones – Hypercalciuria from associated hyperparathyroidism (MEN 1).
- Liver metastases – Occur in up to 70 % of patients with sporadic gastrinomas; they can cause hepatic dysfunction.
- Carcinoid crisis or neuroendocrine tumor progression – Rare but life‑threatening.
When to Seek Emergency Care
- Profuse vomiting that contains blood or looks like coffee grounds.
- Black, tarry stools (melena) or bright red blood per rectum.
- Sudden, severe abdominal pain that does not improve with usual medication.
- Rapid heart rate, dizziness, or fainting – possible signs of severe bleeding or dehydration.
- Unexplained high fever (> 38.5 °C/101 °F) with abdominal pain – could indicate perforated ulcer.
References:
1. NIH National Institute of Diabetes and Digestive and Kidney Diseases. “Zollinger‑Ellison Syndrome.” 2023.
2. J. L. Jensen et al. “Incidence of Gastrinomas in a Nationwide Database.” Annals of Oncology, 2022.
3. B. R. Marx et al. “MEN1 Mutations and Clinical Manifestations.” Cleveland Clinic Journal of Medicine, 2021.
4. Mayo Clinic. “Zollinger‑Ellison Syndrome: Diagnosis & Tests.” 2024.
5. NCCN Guidelines® Neuroendocrine and Pancreatic Tumors, Version 2.2024.
6. WHO Classification of Tumours of the Digestive System, 5th Ed., 2022.