25th May 2025

Gastrinoma

Gastrinomas are associated with gastrin secretion causing acid hypersecretion. This will present as dyspepsia and gastric/peptic ulcers and is also known as Zollinger-Ellison syndrome (ZES). Symptoms also include abdominal pain and diarrhoea. Tumours mainly occur in duodenum and less commonly the pancreas. They are slow growing but can metastasise to lymph nodes and liver. 

All patients with gastrinoma should be screened for MEN as about 25% of cases present as part of MEN. 

Investigations

• Fasting serum gastrin level (raised)
• Gastric pH – <2
• Basal acid output or secretin test – measures gastric acid output via NG tube. Raised with gastrinoma

Note any gastrin/pH investigation will be affected by PPI so these must be held for 2 weeks prior to testing 

• Calcium, parathyroid and prolactin to rule out MEN
• CT/MRI/Endoscopic ultrasound – Tumours can be small and will not always be detectable on imaging
• Somatostatin receptor scintigraphy (SRSS)

Management

• PPI and H2 antagonists will often control symptoms
• Surgical resection if tumour identified
• Surgical exploration is advised in all sporadic (non MEN) cases if not identified on imaging +/- resection