<prompt> Most impoant investigation for diagnosis of Zollinger Ellison syndrome is: March 2013Ca2 infusion testSecretin injection testACTH stimulation testSteroid assay  <response>: 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 