I've had high BUN and creatinine numbers for years. when you are holding a lot of muscle and breaking it down and repairing it daily of course those numbers will be hot
if you want an accurate number then stop working out for 2 weeks and then do bloods, also don't take creatine for a month beforehand, that shit can linger in your system a while
the range numbers labs have are for the common 40 year old couch potato American, its not for lifters. a doctor who doesn't recognize that is an idiot (and believe me they are plentiful)