Decoding drug test results
(April 2021) You’ve sent an employee for a drug test, and you’re waiting for the results. But when you get the results, will you know what they mean? Now, obviously, there are the straightforward results that everyone is familiar with:
- Positive – indicating the presence of the drugs you were testing for was at or above your established cut-off level
- Negative – indicating an absence of drugs at or above your cut-off level
But what if you get a different result? Believe it or not, your test result could come back with something other than positive or negative, including
- Negative dilute – No drugs were detected, but the urine properties were slightly different than expected, possibly because the employee drank a lot of water before the test (for legitimate reasons or to try to “beat” the test), has a medical condition involving the kidneys, or is taking a diuretic.
- Positive dilute – Drugs were present in the urine sample, and the urine concentration was different than expected.
- Adulterated – The laboratory identified an interfering agent (like soap) that was added to the urine sample.
- Substituted – The urine properties, including creatinine levels, are too diminished and not consistent with human urine.
- Invalid – Something was likely added to the urine to interfere with the sample’s properties, but the laboratory cannot pinpoint what it is.
- Canceled – Something went wrong on the vendor’s side, like the seal on the specimen bottle was broken, or some information on the form was not legible.
What do I do now?
Getting a test result that isn’t positive or negative might catch you off guard. And it can be tempting to make assumptions about the meaning of a result and then act on those assumptions. Remember, just because the result isn’t negative, doesn’t mean the individual is using drugs or did something to manipulate the test.
Just as a drug test is an objective tool to enforce your drug-free workplace program, your response to the result needs to be as objective as possible. In fact, there are established best practices for handling all kinds of test results – protocols that have been approved and are mandated by the Department of Transportation (DOT). These are good protocols to follow, even if your employees are not regulated by DOT, to assure your test results are handled consistently and fairly. And while your test results will usually come back as either positive or negative, this way you have a plan in place and will know how to respond if you get a different result.