It's been my experience that deer are not able to identify human urine as urine. If a deer spooks from a spot where youve taken a leak, it's far more likely that you have left other human scent there from your clothing or boots.

I find it funny that some guys wont piss around their stand but have no problem touching saplings and brush with their hands and they dont worry about keeping their boots scent free. Your hands and feet are big scent carriers.