<prompt> Best test for diagnosis of gastrinoma -Ca infusion testSecretin injection testACTH stimulation testSteroid assay  <response>: gastrinoma is a gastrin-producing tumor usually located in the pancreas or the duodenal wall. Gastric acid hypersecretion and aggressive, refractory peptic ulceration result Zollinger-Ellison syndrome. Diagnosis is by measuring serum gastrin levels. Treatment is proton pump inhibitors and surgical removal Post-injection blood samples are collected after 1, 2, 5, 10, and 30 minutes for determination of serum gastrin concentrations. Gastrinoma is strongly indicated in patients who show an increase in serum gastrin concentration of at least 110 pgmL over basal level on any of the post secretin injection samples Ref Davidson edition23rd pg817 