I recently had a pre-employment urinalysis screen. It was 5-panel, 50 ng. EMIT followed by GC/MS for confirming preliminary positives. In anticipation of the test, I stopped smoking two weeks prior. My usual habit of several years is to have a small half-tobacco spliff per day, skipping a day here and there. I end up using about a gram per week, and am slim, weighing 175 at 6'3". Following advice on this forum, I began home-testing myself once I learned of the upcoming screening. A week after my last day smoking, I failed a test. I believe there was a faint, faint, faint line indicating negative, but I was really looking for it. I'm talking about 5% opacity--could well have been a fail and I just wanted to see the line so bad that I wished it were there. I know "any line is a pass," but this was... basically I'd say it wasn't a pass. I was pretty close to the cutoff though, given that 4 days later, I took another at-home test, and passed. A day or two after that, I took another, passed again. The night before the actual test, another pass. The afternoon of the test, I again passed at home. I used several brands of test to rule out the possibility of a false negative. So I had 4 negatives in the week leading up to the test. I decided against dilution--I had an extra glass of water or two the day-of, but I wanted to avoid appearing to have intentionally diluted, since I was doing well so consistently without it. Now, here's the twist. I'm confident I passed the initial test for THC. However, I also take a prescription drug, legitimately, under the care of a doctor. I do not abuse it, and it is done legally at my physician's urging. It is one of the 5 drugs tested for in a 5-panel test. (I'm avoiding saying which one it is, as I think the rules here are to not discuss other drugs, but as this is alegit use of medicine and is relevant to my question, which primarily concerns THC, I'm disclosing the info). When I went for my actual screening, I brought my script for the medicine. My intent was to give it to the tech there, have her mark it on my file, and avoid the possibility of having my sample being sent to GC/MS to confirm the positive result for this substance. However, she rejected it, saying, "It's not our business. If we find anything in your sample, the MRO will call you and you can give him the prescription information then." So now I'm concerned. I think it's about 95% likely I tested negative for THC on the EMIT test, and probably just as likely I was positive for the other (legal! doctor-prescribed!) substance. If and when they send my sample to the lab for the confirmation test, I believe it's probable that I will still be above the 15ng cutoff for THC that the second test uses. Again, I am not concerned about the presence of the other drug in my system, and will be able to provide documentation and my doc's contact info. What I AM concerned about is that this other substance may initiate a more-accurate GC/MS test, which could then reveal the THC (over 15ng, but under 50 ng). Is anyone aware of the likely outcome in this scenario? Will the lab only be looking for the substance that I had an initial positive on, or will they do GC/MS for all five drugs that were being tested for in the first place? I am wondering because as I understand, GC/MS is done to CONFIRM the results of an EMIT. If test #2 doesn't show the same result as test #1, is that considered "confirmation," or is it a scenario in which I'd be asked to provide another sample because the results of the two tests don't sync up? Any insight is appreciated, and I hope that my including the information about my medication doesn't violate the rules of this site. Thanks for your help.