We have a dog with kidney failure, food help?

1.1% difference is really not all that much (as compared to the difference between 23% and 3.3%). You would probably be fine. Do a trial run of 7-10 days and see if you see any problems developing like the dry skin. You can also get the labs drawn again and see what they look like for his overall health situation. Basically, renal failure does not improve with time and your dog is entering the terminal phase of his life.