I just found something that contradicts what I read earlier. This says that there is insufficient evidence of high protein intake causing renal failure in healthy individuals and that it only becomes an issue in people with existing renal problems. Confusing indeed. I'll see if I can find the other studies that I was reading earlier. I was reading them at work so I dont have the links with me now.
http://www.nutritionandmetabolism.com/content/2/1/25