First off, I am sorry for your loss.
I too had a dog pass on from total kidney failure (
Lacey). She was 19 months when she was finally accurately diagnosed, after being ill off and on for a few months. I finally had to insist that my vet do bloodwork to find a cause for her illness and that's when the kidney failure was discovered. In my understanding of the research that I did on kidney issues, unless your dog had been poisoned with antifreeze, no the creatinine levels did not jump in a short time period, but gradually increased. You would've known had your dog been poisoned though, as those symptoms become evident within hours of the poisoning.
I too questioned whether I could've done anything different that may have saved her life, which is why I did major research. Our vet said that her kidney's never developed properly, so it was a birth defect. I did take two things with me from that horrible experience 1) quality of food is very important and 2) periodic blood tests are a good thing and totally worth the money (not to mention convincing your vet that you need them done). I feed a much better food now (not that it would've made any difference in Lacey's case) and I have all my dog's blood tested at least once a year just to monitor levels.
Did your dog have a history of urinary tract infections?