In Zollinger-Ellison syndrome (ZES), which test provides the highest diagnostic sensitivity for confirming hypergastrinaemia in a patient with elevated fasting gastrin and multiple duodenal ulcers?

• A Fasting serum gastrin >1000 pg/mL alone is diagnostic
• B 72-hour fasting serum gastrin plus gastric acid secretion
• C Bombesin stimulation test with gastrin measurement
• D Secretin stimulation test (paradoxical gastrin rise ≥200 pg/mL at 2–10 min) ✓

Explanation

The secretin stimulation test is the gold-standard provocative test for ZES: IV secretin 0.4 µg/kg causes an INCREASE in serum gastrin ≥120 pg/mL (some use ≥200 pg/mL threshold) above baseline in patients with ZES (paradoxical response), while in other causes of hypergastrinaemia (e.g., H. pylori, antral G-cell hyperplasia) gastrin levels fall or remain unchanged. Fasting gastrin >1000 pg/mL with gastric pH <2.0 is presumptively diagnostic without secretin, but overlap exists. Bombesin is used in research, not clinical practice.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.