I have no personal info for you but I found this info at this site:
Blood tests
BLOOD UREA NITROGEN (BUN) - This is a protein metabolyte excreted by the kidney (it is one of the toxins we are concerned about). In a normal animal, the BUN is 25 or so(Normal is 15 to 30). A good goal for BUN in kidney failure is 60-80. Often at the time of diagnosis, BUN is well over 150, 200, or even 300.
Creatinine is usually high (Normal is 1.5 or less)
http://www.myfluffydog.com/dog/health/internalmedicine/renalfailure.php
If you do a search on BW or the internet you should find lots of info.
Stephanie