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So while on my ICU months this year, I had upper levels that were very insistent that we needed to get a urine drug screen on everyone. I would try to make the point that it most likely was not going to change our management of the patient at all. My point was often ignored and after countless urine drug screens obtained during those months, most if not all proved to be of no utility.
Interestingly, Foamcast just put out a podcast about false positives and false negatives on the UDS. What I found most interesting was that ibuprofen can cause a false positive for just about anything under the sun including cocaine, PCP, THC, and barbiturates. Also, the benzos tested on this really only test for oxazepam which is a metabolite of diazepam. So Ativan, Klonopin, and Xanax won’t show up.
Here is the link if you want to read the whole thing. https://foamcast.org/2016/04/26/episode-48-urine-drug-screen-cocaine-and-pcp/
Good information regarding UDS, especially the false neg/pos. I suspect there are also differences in the sensitivities based on the methodology/tech aspects from lab to lab. My practice is to use UDS to either confirm my clinical suspicions, although occasionally find a surprise, and/or to effect and fortify a disposition decision that I want to engender . As the clearance rates of metabolites are markedly individually variable ( think ETOH ranges 20-40/hr depending on the experience of the individual liver ETOH dehydrogenase ) that the presence of for example cocaine does not correlate well with attributing CP as “just cocaine spasm ” .
Lots of crossover positives especially with some of the designer drugs, and innumerable negatives that are individually cleared, UDS are just that a screen…..nothing more. Good reminder of that fact, and keep making your point Chelsea, your correct !!!
Agree with Royce. To this day, I often have to check my bias when the “tox screen lights up like a Christmas tree. The urine tox screen may not be tied to the current medical condition and to hang your diagnostic/therapeutic hat on such a flawed test is not the practice of good medicine. There are just too many false positives/negatives/variables and timing issues to make it a diagnostic test of choice.
Think of it as giving someone who is mildly short of breath thrombolytics for a PE based solely on a positive d-dimer.