The straight dope about the urine toxicology screens
July 27, 2010, 12:39 am
Academic Life in Emergency Medicine has a very handy pocket card listing the causes of false positive results on the urine drug screen, and duration of positive tests after last drug use. It is suitable for printing out and carrying around in a notebook.
Toxcast Says:
i saw the urine screen card on your site. although it has some
helpful info on it, i think many details on it are misleading.
diazepam will not give a positive result for 30 days, and some of the other false
positives/negatives have not been confirmed in the published lit on
this topic. AND, the excellent coca tea paper on which you (LG) are an author is not even mentioned as a common false positive for cocaine metabolites (Euro J EM 2006;13:340). overall, i really think the card stinks and is misleading to the general practitioner and i would give it only a single skull/crossbones on a scale
from 1 to 5.
July 27th, 2010
Leon Says:
Toxcast:
I believe you are correct about diazepam. The article form which the urine screen card to obtained (Amer Family Physician March 1 2010;81:635) says that the urine screen for diazepam is positive for 30 days, but does not provide any reference to support the claim.
As for the European Journal of Emergency Medicine article, a bunch of people in our toxicology group ingested ungodly amounts of (legal) Inca coca tea, after which our urine tests lit up like Roman candles. i believe that you also were an author/victim on that paper. The Inca teas was good (I took mine with honey and lemon) but I really would have preferred darjeeling.
July 28th, 2010