I am usually ordering CMP and BMP labs so I automatically get both. I use both to evaluate the overall picture of the kidney health. Of course, these are indirect indicators. An elderly lady with a Cr of 1.3 may have poor kidney function, as her muscle mass is so low and she really is hanging on to a large percentage of her Cr by failing to clear it. You are right, generally much more useful than the BUN, but we get both together.
