Not a week after being hospitalized for a kidney infection, Mary-Kate Olsen was back on the town again, putting her nephrological health to the test.

We caught up with the not-Ashley celebutwin leaving the Bowery Hotel last night, looking not so worse for the wear after her hospital stay, to the extent that we could actually catch a glimpse of her -- and not just the bat-like eyes that tend to pop out of the night.