This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Most impoant investigation for diagnosis of Zollinger Ellison syndrome is: March 2013 
Select and explain. 
A. Ca2+ infusion test, B. Secretin injection test, C. ACTH stimulation test, D. Steroid assay
B: Secretin injection test
Answer: B: Secretin injection test 
Explanation: Ans. B i.e. Secretin injection test Gastrinoma/ ZES MC site: Duodenum Non beta cell tumour, Neuro-endocrine tumour/ NET secreting: Gastrin Most impoant investigation: Secretin injection test DOC for ZES: Proton pump inhibitors Hepatic metastasis occurs (33%)