I have a wonderful 15-year-old neutered male orange tabby named Sunshine. I love him so much. He is an indoor/outdoor cat but prefers to be outside. I noticed that he suddenly became quite thin in the spring. Our vet did a urine test and told me that he has kidney failure and the best treatment was to feed him KD food. He hated the KD food and wouldn’t eat it so I started giving him Fancy Feast soft food to put on weight this past summer. I also did this because I thought maybe the soft food was easier for him to eat. However, I observed him eat an entire adult rabbit so I realized that he could eat hard food just fine. He’s been just on Purina cat chow since August now and he seems much healthier. I also de-wormed him though since he likes to feast on things that tend to have worms (chipmunks, mice, and bunnies) so it is possible that he had worms and de-worming him made him feel much better.
How could the vet have known just from a simple 5 min. test that he kidney failure? I’m just asking because I know kidney failure is 100% fatal, correct? Maybe he doesn’t have kidney failure. Is this possible that maybe the vet just "thought" he has kidney failure because it’s so common w/ geriatric kitties? Should I spend money for further testing and what would the tests be and what might they reveal?
Sorry for asking so many questions! And much thanks for any information!

