What Do Urine Tests Screen For?
There are two different types of urine tests: immunoassay and gas chromatography/mass spectrometry.
You’ve just got a new job. You’re scheduled to start Monday—but first, they need you to take a drug test. Pee into a cup, hand it in, and they’ll analyze it for foreign or illicit substances. What will they find? What are they even looking for? Here’s what you need to know about urine tests.
Types of Urine Tests
The first thing to understand is that not all urine tests are created equal. There are two different types of urine tests: immunoassay and gas chromatography/mass spectrometry. Immunoassay is much simpler and much cheaper. It can be done “in house,” so to speak, and the results are available fairly quickly.
The problem is, immunoassay testing isn’t effective for all substances. It can also produce both false positives and false negatives. Because of this, many employers consider it only a jumping off point. If someone does test positive in an immunoassay test, then another test is conducted using gas chromatography/mass spectrometry.
GC/MS testing involves sending urine samples to an outside lab, to determine definitively whether drugs are present. The test is more thorough, but it’s also much more expensive. And even with GS/MS, there can still be false negatives. In particular, both immunoassay and GS/MS sometimes have trouble detecting drugs that were taken the same day as the test.
What They’re Testing For
Urine analysis tests for a wide range of substances, including:
- Methadone (which is technically legal)
- Amphetamines and Methamphetamines
- Opiods and Narcotics
Of course, not all tests screen for everything. In fact, in times past, some drug labs would charge separately for every substance they tested for, leading employers to focus only on specific drugs—such as whether or not truck drivers were taking amphetamines to stay awake on the drive.
However, this practice is now condemned by most insurance companies and has become much less common. Still, some employers may choose only to screen for the most common drugs, or the ones most common in their particular field, such as THC and cocaine. The one substance that is typically tested for separately is alcohol. If employers choose to test for it, is generally done with a breathalyzer, rather than a urine test.
It’s important to remember, drugs will remain in your system even after their effects wear off—sometimes long after. Most drugs you can still test positive for up to four days after taking them. In the case of marijuana, particularly with chronic marijuana use, it can stay in your system for a full month.
Even the rigorous GS/MS lab tests aren’t infallible. Some outside factors can cause false positives. If you’re on certain prescription medications, they can read the same as various illicit substances. For instance, many diabetics are prescribed Metformin, which can cause a false positive for amphetamines. Even some over the counter medications, like Benadryl and Tylenol PM, can cause you to test positive for PCP.
You may have also heard that eating poppy seeds can cause a false positive for opioids. It sounds like an urban legend, but it’s actually true. The poppy plant is used to make opium and morphine, and while the seeds have no psychoactive effects, eating even just a few of them on a muffin or a bagel can lead to a false positive on your urine test days later.
Even if you’re completely drug-free, successfully navigating a urine drug test can be a challenge. And a positive result—even a false one—can be detrimental to your chances at employment, both now and in the future. It’s important to go in with your eyes open and understand exactly what you need to do, in order to come out clean.