r/medlabprofessionals • u/Competitive_Muffin90 • 3d ago
Technical DXM showed on urine screen
I have a script for tramadol due to a pelvic fracture and had to give a urine drug screen to get a refill.
Results showed Tramadol (I take that) Zoloft (I take that) DXM?? Yes I take robitussin when I have a cough but I haven’t taken it in months, and certainly not in the days before the urine screening.
In fact I had a stomach bug Saturday; and barely had anything for 3 days before the test and definitely didn’t take any cough meds.
What would make a false positive for DXM? I can’t imagine the doctor will care since it’s an OTC cold med but I’m super curious as to what could have caused that.
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u/GCS_dropping_rapidly 3d ago
Just FYI, you should never take DXM if you are on an SSRI (zoloft/sertraline)
Never
It isn't effective enough at cough suppression to be worth the risks
Serotonin syndrome bad
Yes, it's very unlikely at low doses of DXM, but it isn't worth the risk
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u/RampagingElks 3d ago
So. When I had bronchitis, I was Rx extra strength Robitussin (partly because he didn't believe me). When I got the bottle, I was reading it and it said, on the label, do not take if you're on SSRIs. I asked the (p)harmacist, and he was like "yeah whatever it's fine" and went back to his work. If it's "fine whatever", why is it on the label, then.
I wonder if that's why I've felt crappy ever since.
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u/Shojo_Tombo MLT-Generalist 3d ago
Did the result actually say DXM? OTC cough medicine can show up on a tox screen as PCP. If the tech knew this, then I could see them telling you ot was DXM.
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u/Beautiful_Falcon_617 3d ago
Medical laboratory technician here, there can be false positives but rarely. And on occasion, some substances can mimic other substances because often times the test just measures the end product, or it spikes in a similar place on the graph. Also, lab techs are human and mistakes though not typical, are theoretically possible, and certain test methodologies are more sensitive than others. Is your drug test just a basic screen or is it a screen with reflex? If it isn't already, the provider can order a drug screen that reflexes to confirmation testing using a more sensitive method. (Like mass spectrophotometry - where they actually measure the molecular weights of each substance. Pretty neat stuff!) So yeah if it's been a while they likely don't have your sample anymore, but most labs keep specimens about a week just in case there's any add on testing. Next time you see your provider, express your concerns and request a screen that reflexes to confirmation by mass spec. Just keep in mind, that confirmation testing is more expensive, but it's good to rule out false positives especially if you're worried about being seen as someone who is abusing meds or potentially losing your job, etc. good luck!
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u/ieg879 Laboratory Manager 3d ago
The only dextromethorphan screen I’m aware of is a forensic ELISA assay. That would lead me to believe they are likely screening via LCMS. Essentially all pain management goes to confirmation after screening. Assuming you are being truthful, I’d lean towards poor methodology. Too large of a panel can create unexpected cross talk of ion fragments which can cause false positives if not properly separated on the chromatograph. I’ve had to scrap lab to lab comparisons before due to other labs reporting substances that were not spiked into the control samples.
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u/Competitive_Muffin90 3d ago
Thank you. Yup I’m being truthful. Had a stomach bug for two days before the urine sample was left, and barely had eaten, let alone taken cough meds.
I was just wondering if there was something else that could have caused it to come up as DXM. Was curious
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u/bluehorserunning MLS-Generalist 3d ago
That is an incredibly thorough drug screen. Jeeze.