Can't say that I've ever needed to take a urine test for meds. Never really been on anything, that it was necessary to monitor. I've had blood work, that tested the anti-bodies when I took an Inter-furon Avonex medication for MS, but that was the fullest extent of monitoring my system.

I do know of some people, that have had urine test for prescribed meds.

There are always chances for false negatives, would your doctor be able to follow up your concerns with a blood draw?

One person, that I know, ended up losing a prescription for Oxycotin over her urine test. I forget, specifically, what led to the urinalysis, but it happened, and the meds in her system, didn't match the prescription given. There's a lot of legal issues, when prescribing controlled substances, so it's of no surprise, that your doctors office, may have a new policy. Could, be insurance reasons, as well, that prompted that change.