I am not an "authority" as referenced in the above post nor are my toes "stepped on". I just have a different opinion about who to turn to for professional advice.
I am also not a vet or a nutritionist and I don't believe that online "research" in total has the answer I need to manage my pups who have medical issues.
For that reason, I always, with any of my pups who need a special diet, consult with my vet....OR a board certified vet nutritionist.
I have also managed many pups in various stages of renal failure. I home cooked for one of my beloved pups and he did well for as long as we could keep him doing well. In the end he did succumb to renal failure. This was over a period of 5 - 6 years, so it can be managed IF it is not in end stages when diagnosed.
To find a boarded vet nutritionist, here is a link:
American College of Veterinary Nutrition