What You Need to Know About Drug Testing for Marijuana
The most common method of drug testing in this country for illicit substances is a urinalysis, aka UA. Cannabis has been known to stay in a person’s system for days or even weeks in high enough amounts to produce a positive result on a UA. A positive UA therefore does not necessarily mean that the person is under the influence at the time of testing.
Medical marijuana is legal now in 33 states and commonly being utilized to alleviate problems from medical conditions such as glaucoma, nausea, vomiting, spasms, and pain. If you are using or contemplating medical marijuana for treatment, and are currently employed and potentially subject to random drug testing, then you should educate yourself on the various testing methodologies available. Certain states, such as Arizona, have the ability to fire an employee if he or she tests positive for weed while on the job and performance is being affected. Keep in mind that a urine drug test aka UDS for weed is testing for a cannabinoid metabolites called THC-COOH. This metabolite is produced by the liver, and is indicative of significant metabolic degradation having already taken place. There is no correlation between a positive test and a state of real-time marijuana intoxication.
Unfortunately, this means urine tests are incapable of distinguishing between weekend use, regular use, or on-the-job impairment. Therefore a blood test for cannabis is a more reliable indicator of last use, as it measures the actual presence of THC in the bloodstream. After using medical marijuana, a blood test will register positive for a few hours. In the first 10 minutes of smoking weed, THC levels peak sharply and then drop off dramatically over the next few hours.
Blood tests can also detect for the metabolites of THC similar to the urine testing. It can test for two metabolites, one inactive and one active. The inactive metabolite is THC-COOH and is the same as what is tested for in a UDS. The active one is called 11-OH-THC and is psychoactive. Blood levels mirror those of THC itself, rising 2-6 hours steadily after use. Although it has not been definitively shown in studies, many organizations feel that evaluating the ratios of these three substances are a reliable indicator of recent vs chronic consumption.
Hair testing for marijuana does not measure current use, but from days, weeks, or months past. Hair strand testing evaluates metabolites that have settled in the base of the hair follicle. Shampoos that say they will make for a negative drug test may in fact clean the residue off the hair strands, but eliminating the residue from the hair follicle will be impossible as the metabolites end up in the root of the hair.
Starting medicinal marijuana may help your debilitating condition dramatically. However, if you’re subjected to drug testing, it is beneficial to know which test indicates active use and which will show inactive metabolites.
