Drug Testing 101

On a day to day basis, I receive more questions concerning drug testing than questions concerning policy and procedure - combined. This article provides a basic understanding of drug testing.

How the Body Processes Drugs

Soon after a recreational drug is consumed it starts affecting the brain and body, while at the same time the body starts getting rid of the drug. In order to excrete a drug quickly, the body must convert the drug into a different chemical. This altered chemical is called a drug metabolite.

How Drug Tests Work

Drug tests work by detecting either the actual drug or the drug’s metabolite(s). Some metabolites are “active” and can impair an individual, while some are “inactive” and do not cause impairment. “Active” drugs and “active” metabolites remain in the body for only a short period of time. Some “inactive” drug metabolites can remain in the body for an extended period of time (e.g. Carboxy THC).

We look for drugs and their metabolites in different areas of the body through screening and testing.

Drug Screen vs. Drug Test

A drug screen detects the presence of a drug or drug metabolite. Screens do not reveal how much of a drug or drug metabolite is in the specimen, just its presence above a certain cut-off level. Technically speaking, “drug screen” is the more appropriate term for an instant urine or oral fluid “drug test”. Screens can occasionally produce false positives and false negatives. This is why positive drug screens are considered “presumptive” positive and must be “confirmed” by a laboratory drug test.

A laboratory drug test accomplishes one of two things: it confirms the presumptive positive screen AND reveals how much of the drug or drug metabolite is present, or, nullifies the presumptive positive screen by returning a negative result.

Both screens and tests have a purpose.

Types of Drug Tests and Their Purpose

Drugs and drug metabolites may be found in urine, oral fluid, breath, sweat, blood, and hair. The usefulness of the test selected is dependent on what I want to know as a tester.

For example, if I want to know if an individual is actively under the influence of alcohol, I would select a breath or blood test and look for the chemical ethyl alcohol (drinking alcohol). This is the active chemical that causes impairment.

If I want to know if an individual is remaining abstinent from alcohol while in a treatment program, I would test for alcohol AND for two inactive metabolites of alcohol: ethyl glucuronide (EtG) and phosphatidylethanol (PEth).

EtG can be detected in urine for up to five days after an individual last drank. PEth can be detected in blood for up to 28 days for a chronic heavy drinker, and even longer in hair. If I’m only concerned with current intoxication, running these tests would be unhelpful and a waste of money.

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Ryan West