Which tests will be needed to confirm the diagnosis of gerd?

Clinical history. Usually just a good clinical history and response to acid reducers are enough to diagnose gerd. The gold standard is ph testing of the esophagus with either a catheter or capsule test. An endoscopy will show if there is erosive gerd.
See below. The diagnosis of gerd can usually be made based in a a good history and response to a therapeutic trial. The only way to definitively confirm the diagnosis is either an endoscopy demonstrating reflux changes in the esophagus or a 24-48 hr pH monitor. In simple gerd these are generally not needed.