I am so sorry about your loss. My cat Lucky had to be put to sleep for the same problem.
Rush Limbaugh spoke about his cat dying from a kidney problem. He said that his cat stopped eating and that sounded like what happened to my cat. Do you have any experience with this condition. I was not able to take my cat to the vet because she slipped out into the woods to die. I have been wondering just what happened to her health.