NAD means no abnormality detected. It is a common acronym used in medical shorthand along with SOB (shortness of breath), HR (heart rate), RR (respiratory rate), BS (breath sounds), and many many more. Of course, there are some which are crass and crude and unwelcome in 2019. I’m guessing someone will know about FITH and GOMER. These are altogether inappropriate acronyms in any patient health record.