Investigation

Diagnosis is made on the basis of:

• 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 (1)
• also, with a skilled operator, endoscopic ultrasonography (also combined with biopsy) is also a very sensitive method to detect pancreatico-duodenal tumours

Reference:

1. de Herder WW and Lamberts SWJ. Best Practice & Research Clinical Endocrinology & Metabolism 2004; Volume 18(4): 477-495.