Urine/Blood test tomorrow - questions

[cest.la.vie]

My idiot of a psych has dropped off a blood slip that I have to do tomorrow, and included a urine sample because my overreactive mother told her that I was taking ProPlus (which, incidentally I'm not, I just own some). Apparently some caffeine now and then means I'm a drug addict
Anyway, I'm just wondering what a 'urine analysis for drug screening' tests for/what things would show up on it? Sorry if it's a stupid question. I presume it tests for illegal drugs/prescription meds?

Also, with regards to a blood form, what does ESR mean?

Thanks.

[Animad]

ESR test basically looks for inflammation and can be used to look for infection. Urine tests tend to look for most of the common illegal drugs (or legal one that you could get and take as a form of abuse).

[cest.la.vie]

Thanks :)