Hi sara
no you want to see if protein is in the urine only. You shouldn't see a protein loss in the blood unless there is a much more critical issue.
I read your other posts -- cats rarely get the type of kidney disease which causes protein loss, and benazepril/enalapril is used successfully to reduce damage from that type of kidney disease. The standard "CRF" cat old-age disease does not benefit from benazepril as far as anyone can tell. Individual vets feel it has made a difference and may continue to use it despite the recently published studies.
Do you have the results ofyour cat's urinalysis? Do you know what the specific gravity of the urine was? What were the levels of BUN/creat/phosphorous in the blood ?