# Zollinger-Ellison Syndrome

> Zollinger-Ellison syndrome for NEET-PG Medicine: gastrinoma, refractory peptic ulcers, secretin stimulation test, gastrinoma triangle and MEN1 link.

- Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/zollinger-ellison-syndrome
- Exam / course: NEET-PG · Subject: Medicine
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-08
- Last updated: 2026-10-08
- Reference basis: Harrison's Principles of Internal Medicine; Sleisenger and Fordtran's Gastrointestinal and Liver Disease; Davidson's Principles and Practice of Medicine
- How to cite: "Zollinger-Ellison Syndrome", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/zollinger-ellison-syndrome

## Direct answer

Zollinger-Ellison syndrome is a gastrinoma, a gastrin-secreting neuroendocrine tumour that causes gastric acid hypersecretion and recurrent peptic ulcers, often in the duodenum and sometimes at unusual sites. Diagnosis rests on raised fasting gastrin with gastric hyperacidity, supported by a secretin stimulation test. A significant minority of cases occur as part of MEN1.

## What you must remember

- **Gastrinoma:** A gastrin-secreting neuroendocrine tumour, most often duodenal and sometimes pancreatic; many are malignant at presentation.
- **Gastrinoma triangle:** The junction of the cystic and common bile ducts, the junction of the second and third parts of the duodenum, and the neck and body of the pancreas, where tumours cluster.
- **Clinical clues:** Refractory peptic ulcers, ulcers at jejunal sites, diarrhoea from acid inactivating pancreatic enzymes, and ulcer recurrence after surgery.
- **Acid test:** Fasting hypergastrinaemia with gastric pH below 2 supports the diagnosis.
- **Secretin test:** Intravenous secretin causes a paradoxical rise in serum gastrin in gastrinoma, with a rise above about 120 pg/mL the classic threshold; proton pump inhibitors are stopped first.
- **MEN1 link:** Parathyroid and pituitary tumours in the same patient, so calcium is checked in every case.

## A pathway for ulcers that will not heal

Ulcers that resist standard therapy, especially at jejunal sites, call for a gastrinoma work-up. A 35-year-old man with three duodenal ulcers and a jejunal ulcer after two previous operations, despite high-dose proton pump inhibitor therapy, shows the sequence.

1. **Measure fasting gastrin:** Interpret the value carefully, because proton pump inhibitors raise gastrin and can give a false positive.
2. **Measure gastric pH:** A value below 2 with raised gastrin supports the diagnosis.
3. **Use the secretin test:** If the result is equivocal, a rise in gastrin after secretin supports gastrinoma.
4. **Localise the tumour:** Cross-sectional imaging, endoscopic ultrasound and somatostatin receptor imaging are used.
5. **Check calcium and PTH:** Hypercalcaemia can raise gastrin through hyperparathyroidism, and MEN1 must be considered.
6. **Treat and test for H. pylori:** High-dose proton pump inhibitor therapy controls acid, followed by surgical resection when the tumour is localised and resectable. H. pylori is tested, but its eradication alone does not cure the gastrinoma.

## Where the exam tries to catch you

Four traps recur in questions on this topic.

- **Trap:** reading a high gastrin level on a proton pump inhibitor as diagnostic. — **Correct:** acid suppression raises gastrin through G-cell stimulation, so test off acid suppressants or interpret with gastric pH.
- **Trap:** accepting a gastrinoma diagnosis without checking calcium. — **Correct:** primary hyperparathyroidism can raise gastrin, and a confirmed gastrinoma prompts MEN1 screening.
- **Trap:** treating H. pylori as the single cause of an unusual-site ulcer. — **Correct:** jejunal ulcers, diarrhoea and recurrence after surgery point to Zollinger-Ellison syndrome instead.
- **Trap:** assuming a high gastrin alone proves gastrinoma. — **Correct:** a rise in gastrin after secretin is the feature that separates gastrinoma from other causes of high gastrin.

## Frequently asked questions

### What is the secretin stimulation test used for in Zollinger-Ellison syndrome?

The secretin stimulation test distinguishes gastrinoma from other causes of hypergastrinaemia, because secretin paradoxically raises serum gastrin in gastrinoma. A rise above the classic threshold supports the diagnosis of Zollinger-Ellison syndrome.

### Where do gastrinomas usually occur?

Gastrinomas most often occur in the duodenum, and they cluster in the gastrinoma triangle. This triangle lies between the cystic and common bile ducts, the second and third parts of the duodenum, and the neck and body of the pancreas.

### Why are proton pump inhibitors stopped before testing for Zollinger-Ellison syndrome?

Proton pump inhibitors raise serum gastrin, which can produce a false-positive fasting gastrin, so they are withheld before testing for Zollinger-Ellison syndrome. Gastric pH measurement on acid-suppressing drugs is also unreliable.

### Which endocrine syndrome is associated with Zollinger-Ellison syndrome?

MEN1 is the endocrine syndrome linked to Zollinger-Ellison syndrome, with parathyroid, pituitary and pancreatic tumours occurring in the same patient. Hypercalcaemia should therefore be checked in every patient with a gastrinoma.

### What is the first-line treatment for Zollinger-Ellison syndrome?

High-dose proton pump inhibitor therapy is first-line for Zollinger-Ellison syndrome, controlling acid hypersecretion and healing ulcers. Surgical resection of the tumour is attempted when it is localised and resectable.