Grammar
-(이)라고?
Surprised echo
Form
Last Name + -(이)라고? — « ... ?! », surprised reaction
Function
-(이)라고? repeats a name to express surprise, disbelief, or to ask for confirmation. This is not a complete indirect speech construction.
Why this form?
-(이)야? verifies the identity without necessarily repeating any surprising remarks. (e.g., : 병원이야? — It's a hospital ?)
-냐고? Instead, it refers back to a previous question. (e.g., : 의사냐고? — You're asking if he's a doctor ?)
Examples
병원이라고??! — A hospital ?!
오늘이 시험이라고? — The exam is today ?!