but for your first question or statement. creatine will not cause renal failure in reasonable doses.
its in food, and your body makes it. creatine causing renal failure is like a couple of doses of tylenol causing hepatic failure, there has to be an underlying problem. he already had kidney problems, or it is viral or a progressive disease. ka levels, na etc are all measures as well, as well as urea to my knowledge.
you said he never had kidney problems. did he get a full blood panel done every year at least? if not, then you dont know.