26th May 2025

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)