In the end stage of renal failure, a low body temperature, seizures, and severe depression and coma can result. If you see these signs have your veterinarian evaluate your cat. The veterinarian should do blood and urine tests. Blood tests that are important are the BUN, Creatinine and phosphorous. BUN or blood urea nitrogen is a chemical that the liver makes from ammonia.
Ammonia is absorbed in the gut from the breakdown of dietary protein.
After production in the liver, BUN is excreted by the kidneys. BUN increases in other disease states as well including dehydration and urethral obstruction. The creatinine is a breakdown product of muscle and is excreted by the kidney at a constant rate. Although we do not believe it causes problems when it is high, the creatinine serves as an important marker for kidney function. It is also effected less by dehydration and may help us determine if an elevated BUN is due to renal causes or not.