Does he spray when he's outside? Is he taken out at the same time everyday so he knows when to expect his next outing?
I still think he just needs more water in his diet, his urine is too concentrated and that may bring down the ph level too, just a couple of teaspoons per kitty mixed with their meal.
There is always protein in urine as the kidneys extract unused protein in the blood. If his creatinine & Bun levels were also high, I would be worried about the functioning of the kidneys.
Raw is a QUALITY protein, as long as your ratios in the food is 80% muscle meat 10% bone 10% organs then you are feeding a proper carnivore diet (BTW, do you ensure they are getting some skin for Vit D? a bit of iodized salt?)
Cat maid to:
Puddles, female Himalayan (16 yrs)
Jasper, male Ragdoll ?? (approx 9 yrs)
Sweet Pea, female silver tabby DSH (approx 7 yrs)
Rose semi feral, a cpietra rescue, female tabby (approx 6 yrs)
Snowball RIP (1991-2005)
In a cat's eye, all things belong to cats.-English Proverb
“While we are free to choose our actions, we are not free to choose the consequences of our actions.” Stephen R. Covey