April 17, 2014

Mysteries of the Urine Tox

How useful is a Utox in clinical management? Not very.

But you don’t need an article to tell you that. Sure, there’s always the case where you made a tough diagnosis on a patient with unexplained tachycardia or altered mental status by getting a Utox. But most of the time, it gets ordered pro forma.

Two (of the many) problems with the Utox are the false positives and the false negatives. Attached is a paper that I learned about from my friend  and toxicologist to the stars Leon Gussow.

I would give this paper a 4/10 for overall quality, but what it does have is a excellent list of agents that can cause a false positive for all of the different tests for drugs of abuse. Give it a look over, then keep it somewhere you can access during your next night shift when the 55 year school teacher/father of 2  has a positive screen for amphetamines.  It’s either an episode of Breaking Bad, or the ranitidine he’s taking for reflux.

 Click the link below for a PDF of the full article

Urine Drug Screening: Practical Guide for Clinicians


The other side of the coin is the false negative UTox. The best reviews I’ve seen on this are by Dr. Bryan Hayes from Academic Life in Emergency Medicine. Why does my patient with a lorazepam overdose have a negative UTox for benzodiazepines? Seems like madness, but once you know the basics of how this test works, it makes sense. Read more about benzo Utox here

When testing for narcotics, not all agents are created equally in the eyes of the UTox. Read more about narcotic UTox here



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Awesome article, I know - please share your erudite thoughts...