Hello Rosebud,
Welcome to the Pain Management Forum.
In my opinion there is not an easy "yes" or "no" answer to your question. Normally the answer would be no but there are a lot of variables that come into drug screens. A blood test should obviously be accurate. Urine drug screens done in mass, such as through a PM Clinic has a higher incident of inaccurate results.
Studies have been conducted by reputable sources that indicate these tests can be as high as 60-70% inaccurate. The largest factor is Human Error! Much goes into the final results of urine testing such as an appropriate chain of custody.....proper labeling and so forth. Given all the reading and research I have conducted on this process I would answer your question with....."Yes."
Hope that my input is helpful.
Take Care,
~Tuck
I've read various people who had this complaint with various drugs. I don't know the reason why but hopefully someone else will be able to give you some insight,