Zollinger‑Ellison Syndrome (Gastric Acid Hypersecretion)
Overview
Zollinger‑Ellison syndrome (ZES) is a rare disorder in which one or more gastrin‑producing tumors called gastrinomas develop in the pancreas or duodenum. The excess gastrin stimulates the stomach lining to secrete large amounts of hydrochloric acid, leading to severe peptic ulcer disease, gastro‑esophageal reflux, and malabsorption.
Who it affects: ZES can occur at any age but most commonly presents in adults aged 30‑60. Both sexes are affected equally, though some studies suggest a slight male predominance (≈55%).
Prevalence: The syndrome is very rare, with an estimated incidence of 0.5–2 cases per million person‑years worldwide and a prevalence of roughly 1–3 per 100,000 people.1 Approximately 20–30% of cases arise as part of the inherited condition Multiple Endocrine Neoplasia type 1 (MEN‑1).2
Symptoms
Because the hallmark of ZES is gastric acid hypersecretion, symptoms often relate to acid‑related damage throughout the gastrointestinal (GI) tract.
- Recurrent or refractory peptic ulcers – ulcers that fail to heal and may occur beyond the duodenum (e.g., jejunum, ileum).
- Abdominal pain – usually epigastric, burning, or crampy; may worsen after meals.
- Diarrhea – acidic chyme inactivates pancreatic enzymes and damages the intestinal lining, causing watery stools.
- Steatorrhea (fatty stools) – malabsorption of fat leads to foul‑smelling, pale stools.
- Weight loss – secondary to malabsorption and chronic diarrhea.
- Heartburn / gastro‑esophageal reflux disease (GERD) – excess acid irritates the esophagus.
- Nausea and vomiting – especially if ulcer complications such as obstruction develop.
- Upper GI bleeding – melena or hematemesis can occur when ulcers erode blood vessels.
- Perforation – rare but life‑threatening; presents with sudden severe abdominal pain and peritoneal signs.
- Gastroparesis – delayed gastric emptying in some patients due to acid‑induced nerve damage.
- Symptoms of MEN‑1 association – hyperparathyroidism (kidney stones, bone pain) or pituitary tumors (headaches, vision changes).
Symptoms may be intermittent at first, but as the gastrinoma grows or multiple tumors develop, they typically become chronic and increasingly severe.
Causes and Risk Factors
Underlying cause
ZES is caused by neuroendocrine tumors (NETs) that secrete gastrin. Most gastrinomas (≈80%) arise in the “gastrinoma triangle,” an anatomic zone bounded by the cystic duct, the junction of the second and third portions of the duodenum, and the head of the pancreas.
Genetic risk factors
- Multiple Endocrine Neoplasia type 1 (MEN‑1) – autosomal‑dominant mutation of the MEN1 gene; accounts for 20–30% of ZES cases.
- Familial gastrinoma syndrome – rare, inherited gastrinoma without other MEN‑1 features.
Other risk factors
- Age 30‑60 – peak incidence.
- Male sex – slight predominance.
- Chronic gastritis – does not cause ZES but may mask early symptoms.
Environmental factors (diet, smoking, alcohol) do not appear to cause ZES, though they can exacerbate ulcer disease.
Diagnosis
Because symptoms overlap with common ulcer disease, a high index of suspicion is required, especially when ulcers are refractory to standard therapy.
Initial Work‑up
- Serum gastrin level – fasting gastrin >1000 pg/mL (normal <100 pg/mL) strongly suggests ZES; values 2–3× upper limit with acidic gastric pH are also diagnostic.
- Secretin stimulation test – injection of secretin paradoxically raises gastrin in ZES; a rise >120 pg/mL is diagnostic.
- Gastric pH measurement – a pH <2 confirms acid hypersecretion.
Imaging to locate gastrinomas
- Multiphasic CT or MRI – first‑line cross‑sectional imaging; detects tumors >1 cm.
- Somatostatin receptor scintigraphy (Octreoscan) or Ga‑68 DOTATATE PET/CT – highly sensitive for NETs, especially small or metastatic lesions.
- Endoscopic ultrasound (EUS) – excellent for pancreatic head lesions <1 cm.
- Selective arterial secretagogue injection (SASI) test – used when non‑invasive imaging is negative but suspicion remains.
Assessment for MEN‑1
If MEN‑1 is suspected, patients undergo:
- Serum calcium and parathyroid hormone (PTH) testing.
- Pituitary hormone panel (prolactin, IGF‑1).
- Genetic testing for MEN1 mutation.
Biopsy
Fine‑needle aspiration (FNA) of a suspected lesion may be performed for histology, but diagnosis can often be established without tissue confirmation.
Treatment Options
Management aims to (1) control acid hypersecretion, (2) eradicate or control the tumor, and (3) address complications.
Acid‑Suppressive Medications
- High‑dose proton pump inhibitors (PPIs) – omeprazole 40–80 mg daily, esomeprazole 40–80 mg, or equivalent; most patients achieve symptom control.
- Potassium‑competitive acid blockers (P‑CABs) – e.g., vonoprazan (available in some countries) offers rapid, potent acid suppression.
- PPIs are usually continued long‑term; dose tapering is attempted only after tumor resection and confirmed normalization of gastrin.
Surgical Management
Curative surgery is the goal when feasible.
- Localized gastrinoma – enucleation or pancreaticoduodenectomy (Whipple) depending on size and location.
- Multiple or metastatic disease – debulking surgery plus liver-directed therapies (radiofrequency ablation, hepatic artery embolization).
- In MEN‑1 patients, an aggressive surgical approach is controversial because of high recurrence rates; many are managed medically unless tumors exceed 2 cm or cause severe symptoms.
Medical Therapy for Tumor Control
- Somatostatin analogues (octreotide, lanreotide) – bind somatostatin receptors, reduce gastrin secretion and may inhibit tumor growth.
- Targeted therapies – everolimus (mTOR inhibitor) or sunitinib (tyrosine‑kinase inhibitor) are approved for progressive pancreatic NETs.
- Peptide receptor radionuclide therapy (PRRT) – ^177Lu‑DOTATATE for patients with somatostatin‑receptor‑positive metastatic disease.
- Chemotherapy – rarely needed; reserved for high‑grade or rapidly progressive NETs.
Lifestyle & Supportive Measures
- Small, frequent meals; avoid large fatty meals that stimulate acid.
- Limit caffeine, alcohol, nicotine, and spicy foods that aggravate ulcer symptoms.
- Calcium and vitamin D supplementation if malabsorption leads to deficiency.
- Vaccination against Helicobacter pylori* (if present) and routine immunizations (influenza, pneumococcal) because chronic acid suppression can increase infection risk.
Living with Zollinger‑Ellison Syndrome (gastric acid hypersecretion)
Daily Management Tips
- Medication adherence – take PPIs on an empty stomach, 30–60 minutes before breakfast; never skip doses.
- Monitor symptoms – keep a diary of pain, stool consistency, and any bleeding; report new or worsening signs to your gastroenterologist.
- Regular follow‑up labs – fasting gastrin and serum calcium every 6‑12 months; liver function tests if you have liver metastases.
- Imaging surveillance – CT or MRI every 12–18 months for tumor monitoring; more frequent if disease is active.
- Nutrition – consider a dietitian consult; a low‑fat, high‑protein diet can improve nutrient absorption.
- Bone health – DEXA scan every 2–3 years if you have MEN‑1–related hyperparathyroidism or chronic malabsorption.
- Psychosocial support – chronic disease can cause anxiety; support groups and counseling are valuable.
Medication Safety
Long‑term high‑dose PPIs have been linked to:
- Increased risk of Clostridioides difficile infection.
- Hypomagnesemia, vitamin B12 deficiency, and bone fractures.
Regular labs (magnesium, B12, calcium) and bone density checks help mitigate these risks.
Prevention
Because ZES is primarily a tumor‑driven condition, primary prevention is limited.
- Genetic counseling – if you have a family history of MEN‑1, undergo genetic testing and discuss surveillance protocols.
- Avoid chronic gastric irritation – treat H. pylori infection promptly; limit NSAID use, which can mask ulcer pain.
- Healthy lifestyle – smoking cessation, moderate alcohol, and balanced nutrition support overall GI health.
Complications
If untreated or inadequately controlled, ZES can lead to serious outcomes:
- Refractory, bleeding peptic ulcers – may require endoscopic hemostasis or surgery.
- Ulcer perforation – acute surgical emergency.
- Gastric outlet obstruction – due to scarring or tumor mass effect.
- Malabsorption & nutritional deficiencies – iron, calcium, vitamin D, B12.
- Renal stones and osteoporosis – secondary to hyperparathyroidism in MEN‑1.
- Liver metastases – occur in up to 50% of sporadic gastrinomas; reduce survival if not treated.
- Reduced quality of life – chronic pain, diarrhea, and anxiety.
When to Seek Emergency Care
- Sudden, severe abdominal pain that does not improve with medication.
- Vomiting blood (hematemesis) or material that looks like coffee grounds.
- Black, tarry stools (melena) indicating GI bleeding.
- Signs of perforation: rigid abdomen, fever, and rapid breathing.
- Severe dehydration from uncontrolled diarrhea (dry mouth, dizziness, low urine output).
- New onset confusion or fainting, which may signal severe blood loss or electrolyte imbalance.
References
- Mayo Clinic. Zollinger‑Ellison Syndrome. Updated 2023.
- Gear, J. et al. “Zollinger‑Ellison syndrome and MEN‑1.” Journal of Clinical Endocrinology & Metabolism, 2019;104(5):1650‑1660.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Zollinger‑Ellison Syndrome. Accessed April 2026.
- World Health Organization. Peptic ulcer disease fact sheet. 2022.
- Cleveland Clinic. Zollinger‑Ellison Syndrome. Updated 2024.
- Strobel, R. & Bovee, J. “Management of Gastric Acid Hypersecretion in ZES.” Gastroenterology Review, 2022;18(3):112‑124.