By Benjamin Chambers, June 02 2010
If you are involved in running a juvenile drug court, do you ask any of the following questions when you get UA results back for your clients? And do these affect how you or the court sanctions the young person?
- "How positive is s/he?"
- "Are his/her levels increasing or decreasing?"
- "Does the result mean s/he just used?"
Those are the wrong questions to ask -- and are especially concerning if teens are being sanctioned based on the answers to these questions -- according to "Urine Drug Concentrations: The Scientific Rationale For Eliminating The Use Of Drug Test Levels In Drug Court Proceedings," by Paul L. Cary, director of the Toxicology and Drug Monitoring Laboratory at University of Missouri Health Care in Columbia Missouri. Though this fact sheet was published by the National Drug Court Institute in January 2004, it's still relevant today.
Here's my gloss of the article:
- UAs cannot reliably tell you how much the client used, or when.
Urine drug tests are qualitative, not quantitative -- they can only give you a positive/negative result. There is no scientific basis to use a single UA to decide whether or not a client has just used, or to determine whether or not a client is still using or has begun new use.
- But the lab gives me numbers with each result! Shouldn't I use them?
No. Labs give them out the numbers because court workers ask for them -- not because those numbers can tell you anything more than the positive/negative result itself.
- But the courts have used Blood Alcohol Content (BAC) to measure decreasing/increasing use for years!
Yes. But alcohol is a simple molecule, and drugs are complex - meaning that they test very differently. Blood is also very different from urine when it comes to testing. Bottom line is that one can interpret BAC results to determine the amount of alcohol in the system; UA results cannot be used the same way.
- Stick with positive/negative.
The lesson to be learned is to not over-interpret UA results. They can only tell us whether use has occurred -- not when, or how much. Yes, we know that THC takes a while to leave the system, as do some other drugs, so with some clients, we can expect to see multiple positives before we see a negative, even if they've quit using. In other words, repeat testing of clients at regular intervals can improve the interpretation of positive results. Multiple positives over a period of time reinforce the conclusion that an individual may be regularly using the drug(s) being detected -- but looking to levels to get verification that the client hasn't used again is a bad idea. The important thing is to keep testing, and to keep in mind the general guidelines for how long it takes for specific drugs to leave the system.
- It is possible to use creatinine concentrations to help you compare UA tests in a meaningful way if you're testing for THC, according to another article by Mr. Cary. But creatinine concentrations aren't tested as a matter of course and would, I imagine, be cost-prohibitive to do all the time.
- How long does it take cannibinoids to leave the system? Contrary to popular wisdom, it's not 30 days. Check out this piece by Mr. Cary on the "marijuana detection window" (it starts on p. 23).
- Mr. Cary wrote a post for us recently on the importance of observed UA collections.
Updated: February 08 2018