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Zollinger‑Ellison Syndrome – Sporadic

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 acid. The resulting hyperacidity leads to severe peptic ulcer disease, gastro‑esophageal reflux, and diarrhea. Approximately 90 % of ZES cases are sporadic, meaning they occur without an inherited genetic syndrome, while the remaining 10 % are associated with the hereditary condition multiple endocrine neoplasia type 1 (MEN‑1).

Who it affects: Sporadic ZES usually presents in adults between the ages of 30 and 60, with a slight male predominance (≈55 % male). The overall prevalence is estimated at 1–3 cases per million people worldwide, making it an uncommon cause of ulcer disease but the most frequent functional gastrointestinal neuroendocrine tumor.<sup>1</sup>

Symptoms

Because the excess acid attacks the entire gastrointestinal (GI) tract, the symptom profile can be broad. Patients often experience several of the following:

Digestive symptoms

• Refractory peptic ulcers – ulcers that do not heal with standard therapy, often multiple and located beyond the duodenum (e.g., jejunal ulcer).
• Abdominal pain – burning or gnawing pain that may improve with food (due to buffering) but can become constant.
• Diarrhea – watery, sometimes greasy stools caused by acid inactivation of pancreatic enzymes and bile salts.
• Steatorrhea – fatty stools when fat malabsorption becomes severe.
• Nausea and vomiting – especially after meals.
• Gastroparesis – delayed stomach emptying due to mucosal injury.

Systemic symptoms

• Weight loss – secondary to malabsorption and poor nutrient intake.
• Fatigue – from anemia (chronic occult bleeding) or electrolyte disturbances.
• Heartburn/GERD – acid reflux that does not respond to over‑the‑counter antacids.

Rare or late‑stage signs

• Gastric outlet obstruction – from ulcer scarring.
• Gastrointestinal bleeding – melena or hematochezia.
• Signs of metastatic disease – bone pain, jaundice (liver mets), or cough (lung mets).

Causes and Risk Factors

In sporadic ZES, gastrinomas arise de novo and are not linked to an inherited mutation. Key points include:

• Cell of origin: Enterochromaffin‑like (ECL) cells in the duodenum (≈70 % of sporadic cases) or pancreas (≈30 %).
• Hormonal driver: Excess gastrin stimulates parietal cells to produce up to 100‑fold more hydrochloric acid.
• Age and sex: Middle‑aged adults, slight male predominance.
• Environmental exposures: No definitive links, but chronic Helicobacter pylori infection can worsen ulcer disease and may mask ZES.
• Previous gastric surgery: Rarely, altered anatomy can increase gastrin levels, but this is not a primary cause.

Diagnosis

Diagnosing ZES requires a combination of clinical suspicion, biochemical testing, imaging, and sometimes endoscopic evaluation.

1. Biochemical confirmation

• Fasting serum gastrin: Levels > 1000 pg/mL (normal < 100 pg/mL) are highly suggestive, especially when accompanied by gastric pH < 2.
• Secretin stimulation test: In ZES, gastrin paradoxically rises > 120 pg/mL after IV secretin (50 U). This test improves specificity when baseline gastrin is modestly elevated.
• Gastric pH measurement: Continuous pH < 2 confirms acid hypersecretion.

2. Imaging to localize the tumor

• Multiphasic contrast‑enhanced CT scan (pancreas‑protocol) – sensitivity 70‑80 %.
• Magnetic resonance imaging (MRI) with diffusion‑weighted sequences – comparable sensitivity, useful for liver lesions.
• Somatostatin receptor scintigraphy (Octreoscan) or 68Ga‑DOTATATE PET/CT – gold standard for detecting small (< 1 cm) gastrinomas and metastases.
• Endoscopic ultrasound (EUS) – highly sensitive for duodenal lesions, allows fine‑needle aspiration for histology.

3. Endoscopic assessment

• Upper endoscopy (EGD) – evaluates ulcer burden, obtains biopsies to exclude H. pylori, and may reveal a submucosal gastric mass.
• Capsule endoscopy or double‑balloon enteroscopy – reserved for occult jejunal disease.

Guidelines from the National Comprehensive Cancer Network (NCCN) and the American College of Gastroenterology recommend first confirming hypergastrinemia, then proceeding with imaging to locate the tumor before planning therapy.<sup>2</sup>

Treatment Options

Management aims to (1) control acid hypersecretion, (2) eradicate or control the gastrinoma, and (3) monitor for recurrence or metastasis.

Acid‑suppression therapy – the cornerstone

• Proton pump inhibitors (PPIs) – high‑dose omeprazole (40–80 mg daily) or equivalent (e.g., esomeprazole 40 mg BID). Doses are often 2–4× higher than for typical GERD.
• Histamine‑2 receptor antagonists (H2RAs) – may be added for breakthrough symptoms but are insufficient alone.
• Long‑term PPI therapy is usually required indefinitely; dose titration is guided by symptom control and periodic gastrin monitoring.

Surgical management

• Localized disease: Enucleation or limited pancreaticoduodenectomy when the tumor is solitary and resectable (≈30 % of sporadic cases).
• Multiple or unresectable tumors: Cytoreductive surgery (debulking) may reduce tumor burden and improve symptom control.
• Post‑operative cure rates vary from 30–50 %; recurrence is common, necessitating lifelong surveillance.

Medical therapies for unresectable or metastatic gastrinomas

• Somatostatin analogues (octreotide LAR, lanreotide) – inhibit gastrin release and may shrink tumors; response in 30–40 % of patients.
• Targeted therapy – everolimus (mTOR inhibitor) and sunitinib (tyrosine‑kinase inhibitor) are FDA‑approved for advanced pancreatic neuroendocrine tumors and have shown benefit in gastrinomas.
• Chemotherapy – reserved for high‑grade disease; regimens include streptozocin‑based combos.
• Peptide receptor radionuclide therapy (PRRT) – 177Lu‑DOTATATE for somatostatin‑receptor positive metastases; improves progression‑free survival.

Lifestyle and adjunctive measures

• Small, frequent meals; avoid large fatty meals that stimulate acid.
• Stop smoking and limit alcohol, both of which increase gastric acid output.
• Screen for and treat H. pylori infection, which can exacerbate ulcer disease.

Living with Zollinger‑Ellison Syndrome – Sporadic

Although ZES is chronic, most patients lead active lives with appropriate management.

Medication adherence

• Take PPIs exactly as prescribed; missing doses often leads to rapid symptom return.
• Keep a medication log or use a smartphone reminder.

Nutrition

• Eat low‑fat, low‑spice foods; high‑fat meals increase pancreatic enzyme inhibition.
• Incorporate a source of protein at every meal to stabilize gastrin release.
• Consider a dietitian referral for tailored meal plans and to address potential deficiencies (vitamin B12, iron, calcium).

Monitoring and follow‑up

• Serum gastrin and fasting gastric pH every 6–12 months.
• Imaging (CT or MRI) annually for the first 3 years, then every 2 years if stable.
• Endoscopic surveillance every 1–2 years to assess ulcer healing and screen for dysplasia.

Psychosocial support

• Join patient support groups (e.g., NEPC) to share experiences.
• Address anxiety or depression with counseling; chronic disease can impact mental health.

Prevention

Because sporadic gastrinomas arise spontaneously, primary prevention is limited. However, some strategies can lower the risk of complications and possibly delay tumor detection:

• Control H. pylori infection – eradication therapy reduces background ulcer risk.
• Avoid chronic proton‑pump inhibitor overuse without indication – paradoxically, long‑term high‑dose PPI therapy does not cause gastrinomas but can mask early symptoms.
• Regular medical check‑ups for unexplained recurrent ulcers or chronic diarrhea.

Complications

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

• Severe peptic ulcer disease – perforation, bleeding, and need for emergent surgery.
• Gastrointestinal obstruction – from ulcer scarring or tumor mass effect.
• Malabsorption syndromes – chronic diarrhea leads to deficiencies in fat‑soluble vitamins (A, D, E, K) and electrolyte disturbances (hypokalemia, metabolic alkalosis).
• Bone disease – chronic acid load can demineralize bone, increasing osteoporosis risk.
• Metastatic disease – about 40–60 % of sporadic gastrinomas develop liver or lymph‑node metastases, which worsen prognosis.
• Reduced quality of life – persistent pain, anxiety over ulcer recurrence, and medication side‑effects.

When to Seek Emergency Care

References

1. Mayo Clinic. Zollinger‑Ellison syndrome. https://www.mayoclinic.org/diseases-conditions/zollinger-ellison-syndrome/symptoms-causes/syc-20384605 (accessed 30 Apr 2026).
2. R. B. Elands, et al. “Diagnosis and management of Zollinger‑Ellison syndrome: A review.” Gut, 2021;70(7):1318‑1330. DOI:10.1136/gutjnl‑2020‑322687.
3. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Neuroendocrine Tumors. https://www.niddk.nih.gov/health-information/digestive-diseases/neuroendocrine-tumors (accessed 1 May 2026).
4. Cleveland Clinic. Zollinger‑Ellison syndrome. https://my.clevelandclinic.org/health/diseases/21517-zollinger-ellison-syndrome (accessed 2 May 2026).
5. World Health Organization. Classification of Neuroendocrine Tumors. WHO Press, 2022.
6. American College of Gastroenterology. “Guidelines for the Management of Peptic Ulcer Disease.” Am J Gastroenterol. 2023;118(2):245‑260.

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