Investigation

Diagnosis is made on the basis of: (1,2)

• high fasting plasma gastrin
• high gastric acid secretion:
  • usually in excess of 100 mmol/h
• diminished response to pentagastrin

localisation of tumour:

• demonstrable pancreatic or gastrointestinal tumour - by CT or venous sampling for gastrin
• more than 90% of gastrinomas have somatostatin receptors, and somatostatin receptor scintigraphy has been reported to be an especially sensitive method to image gastrinomas
• also, with a skilled operator, endoscopic ultrasonography (also combined with biopsy) is also a very sensitive method to detect pancreatico-duodenal tumours

References:

1. Zimmer V, Glanemann M, Lammert F; Zollinger-Ellison syndrome. CMAJ. 2019 Dec 9;191(49)
2. Epelboym I, Mazeh H; Zollinger-Ellison syndrome: classical considerations and current controversies. Oncologist. 2014;19(1):44-50.