from what I have learned - and this comes from the study of Shivambu which is over 5000 years old method of using UT for healing the urine stream should be treated like a snake, the head and the tail of the snake are not good to use and poisonous but the middles is good.
if you care to learn about my source it comes from a Rasa Tantra group which goes under the name of Salvation Science. There's heaps of information linking UT through many religious texts and ancient healing documents. The website is here :
I can't say I have read the whole site. The amount of information is huge, some volumes having over 200 pages to them alone but it's a great read and there are many interesting bits of information, both spiritual and scientific.