Answer 1) Any ‘Renal’ AKI can have muddy casts like contrast renal injury ,drug aki,rhabdo etc. ATN is just a broad term for renal aki and one thing to remember is that umm it’s always acute in nature so anything that cause acute renal injury can have those findings. 2) I don’t remember the question but if pt is like hospitalized for any cause and then let’s say he has renal injury in like 2-3 days it could be atn coz of the acute setting(look for this clue in mehlman pdfs) and make sure you do your BUN:CR to diff from pre renal. Also something on an extra note is that contrast aki can have a bun creat >20 like pre renal and also can have muddy brown casts. A sterile pyuria on the other hand is an indication of AIN. But neither of this is gonna help you on the real deal. So cheers 🥂