Can a doctor tell if you are a virgin through urine?

Since this is the first answer to this very recently asked question, I would have to guess that the answer is "no".

Blood and urine tests only measure specific biological processes - like the function of one's liver, or the amount of calcium in the bloodstream, etc. Since the effect of having had intercourse for the first time does not result in a biochemical change - i.e. it does not prompt the increase in hormones etc - then "loss of virginity" could not be measured by a blood or urine test.

Unless, of course, if having had intercourse for the first time results in pregnancy - since that certainly can be measured by a blood or urine test!