If the urine is indeed filtered such that it is (mostly) pure and free of contaminants,
it is the liver then, and the kidneys that take on, hold onto, and process the burden. Still, all sorts of bacteria and microscopic parasites are most likely also excreted in the urine: those in the blood, as well as some of what resides in the liver and kidneys, and that would include excess minerals that presumably the body doesn't need) unless one were very pure, mostly fruitarian, etc.--
but I suppose these too, might all fall into that class of things 'reintroduced to the body' as a sort of 'wake-up'. In that sense, it would appear that UT is a highy personalized form of immune system restorative.
I can (more and more) easily imagine the benefits, combined with a very good diet and mindstate, while (still) I have a great difficulty imagining it in relation to your average very sick, toxic, excess protein-laden individual.