How Drug Testing Identifies Illicit Substances in the Human Body

Believe it or not, drug tests do not always look for drugs in your system. Drug tests search for drug metabolites. After the body has taken in a substance, the end product will look much different from when it first passed through your system. Alcohol, for example, goes down the throat as beer, but it looks different as the liver oxidizes the substance. In fact, it comes out as water. When drugs like methamphetamine or marijuana enter the body in psychedelic form, it exits as a metabolite.

Urine Test

An employer’s most common on site drug screening involves the urine test. The company uses a collection facility for convenience and to allow the hiring team to focus on the results of the test. You have two types of urinalysis tests: First, you have a pre employment drug screening, and second, you have a drug test. A drug test and a drug screen will be different. The drug screen usually comes first, and it will follow up with a drug test if needed.

How Long Will Drugs Be Detected in the Urine?

Detection of metabolites in the urine will depend on the drug. For example, methamphetamine’s can be detected for between two to 10 days. Meanwhile, marijuana or THC can be found in urine for between two to four days. Cocaine will also be two to four days, and PCP takes between 14 to 30 days to leave the urine. It also depends on the frequency of drug use.

For complete accuracy with urinalysis, it requires a confirmation of results. To lower costs, sometimes employers will only use a drug screen, but a drug screen sometimes gives you false positives if it detects things like poppy seeds or ibuprofen, but it’s faster and less expensive.

Drug Tests: The Science

After a company has decided on a drug test, they will implement based on the instructions of the provider. You can only make a truly informed decision when you know what the screens can do and what they cannot do, and it can help an employer assess a drug screen. With urinalysis, the enzymes will be utilized for conversion of NAD+ to NADH. The drug test facility will measure on a spectrometer to give a semi-quantitative measurement of the drug metabolites within the system.

The Chemistry and How It Works

Drug metabolites can be found from two possible sources: the lab and the donor. The tester will add three reagents to the urine sample to complete the test. Reagent 1 will have IGG antisheep antibody, which will be specific for analyzing a certain drug metabolite. With Reagent 2, this contains enzyme G6PD and will be attached to the drug metabolite. Finally, you have substrate G6P, which serves the role of an intermediate compound. It will neither be produced nor consumed, but testing facilities use it to proceed with the reaction.

The Results: What Happens Next

Your key result will determine if the antibody reacts to the drug metabolite from either the laboratory’s metabolite or what was given from the donor. If the antibody reacts with the donor’s sample, that means it is positive. Should the antibody react to the metabolite from the lab, however, the sample is negative because metabolite attached itself to the G6PD sample, and when it does this, it blocks the active site of the G6PD. That also means it cannot attach to the NAD+, which will be required for a positive result.

What a Positive Test Means

Positive drug tests mean the antibody had been consumed by the metabolite of the donor, and it did not react with the metabolite from the lab. When this happens, the G6PD allows for the NAD+ to bind, and it will be reduced to NADH as a result. NADH will give off a distinct color, and after a positive test has been returned, the second drug test can be implemented.

Why drug test employees? A survey showed around 75 percent of illicit drug users over the age of 18 are employed. That means 42,000 Americans come to work stoned on any given day. Employees who use drugs are five times more likely to file a workers’ compensation claim, and they’re 10 times more likely to miss work. On top of that, they’re 33 percent less productive than their coworkers. This is why many employers require drug tests.