Zollinger-Ellison syndrome is characterized by all of the following except -

Important points that should raise the possibility of ZES in patients with duodenal ulcer. ulcers in unusual locations i.e. postbulbar ulcers recurrent or refractory ulcers ulcers with diarrhoea multiple ulcers ulcers associated with prominent gastric folds ulcers with findings s/o MEN-1 (endocrinopathy, family history of ulcer or endocrinopathy, nephrolithiasis) ulcers without H. pylori infection