The only way to tell if kidneys are truely damaged is to have a biopsy. It will tell if there are permanent lesions and how much damage has been done...if any. High protein in the urine is a sign of damage, there should be little if any excreted....200mgs tops. Regardless of how much you eat or how much muscle you have. Look for foamy pee as a sign. If so, get it checked out.
The kidneys don't repair as the liver or other organs do.
Was he a tren user?
I have never been convinced that tren affects kidneys can any show proof of this? I have heard this debate for years and no solid proof on one side or the other