Originally Posted by LynMarie
My cat, Merlin, is 15 years old and had slightly elevated Bun (38) and Creatinine (2.5) levels on his last two blood tests. My vet says he has kidney disease, but his specific gravity is 1.050 (high normal) which I've read means that he has a pre-renal issue, NOT kidney disease.
Sounds like you have been doing your homework.
As a general rule for tubular renal disease the concentrating ability of the kidneys will lost even BEFORE the BUN and creatinine will be elevated. There is a subset of cats that can retain the ability to concentrate urine and still have renal disease.
Was a complete urinalysis done? What is the protein level in the urine? Have radiographs or ultrasound been done?
Is there dehydration present which may explain the BUN and creatinine elevations as pre-renal?
Also do you know what the albumin, total protein and phosphorus levels are? Can you get these values?