A drug test involves a technical analysis of a biological specimen, such as urine, blood, oral fluid or hair, to determine whether the bearer consumes certain illegal drugs or prescription medications. Among the many tests administered, urine drug screen is one of the most common.
A urine drug test, also referred to as a urine drug screen or a UDS, is quick and painless and can be used to determine possible substance abuse problems. There are two identified ways to pass a urine drug test: through abstinence or through substitution.
Types of Urine Drug Tests
Between the two types of urine drug tests available, immunoassay is the most common. But while it’s cost-effective and produces result fast, it fails to pick up on all narcotics. There are times when it also shows false positives. A false positive means the test results show positive for drugs even though no substance have been taken. In the case of marijuana, for example, since its metabolite is fairly unique, false positives seldom occur.
In this case, you’ll be given a second type of test, called a gas chromatography or a mass spectrometry. This is similar to immunoassay in terms of specimen acquisition. These are pricier and their results take longer, but the chances of getting a false positive are very low.
Understanding the Results
Immunoassays don’t measure drugs themselves. Instead, these tests measure how drug use affects the body’s ability to create antigen-antibody complexes. The results are expressed in ng/mL (nanograms per milliliter).
As the test is based on a cutoff point, any number below and it is recorded as a negative screen, whereas those above the cutoff point are interpreted as a positive screen. People in charge of the tests usually provide results either as positive or negative instead of presenting them through numeric values.
Many immunoassay tests don’t even display the ng/mL measurements. To determine if the patient passes the urine drug test, a test trip that turns into different colors is used. In case the results show positive for drugs you believe you have not taken, request a gas chromatography immediately.