How Do Urine Test Strips Work?

What's The Purpose of Urine Test Strips?

A drug test strip is a piece of plastic or paper used to detect the presence of drugs in biological materials such as blood or urine. The strip contains a chemical pad or reagents that react or change color when in contact with the biological specimen. It works based on the drug substance and/or its metabolites competitively binding to the testing strip.

Urine is the most widely utilized biological specimen for drug testing. This is because it is easy to obtain, and the process is straightforward. This allows just about anyone to perform the test and perform it accurately. Drug testing strips are one of the most cost-effective and risk-free screening methods for drug abuse or dependence.

There are two types of testing strips, multi-drug, and single drug. The multi-drug options test for various drugs is a good choice if you are doing a pre-employment screen. Single drug testing only tests for one drug in a patient’s system. This is used for those that are known to take certain drugs. Oftentimes, we see this for those in drug rehab, for example.

How Do Drug Test Strips Work?

When submerged, drug testing strips provide an immunochemical reaction between the antigens and antibodies to break down specific chemical components in the samples. The assay is based on the notion of competitive antibody binding between drug conjugate and the drug present in the urine sample.

A drug in a urine specimen competes with the drug’s conjugate for a predetermined amount of antibody dye conjugate. When the drug quantity is equal to or more than the cut-off level, drug conjugate binding to the antibody is prohibited. As a result, if the urine sample tests positive for a drug, the colored band does not appear on the test line zone. A colored band shows that there is no drug or that the amount of drug is less than the usual cut-off level.

For example, while screening for any drug in the urine samples, such as MAMP, OPI, or THC, the presence of any drug would cause it to compete with the drug conjugate for a predetermined amount of the antibody dye conjugate. The binding of the drug conjugate to the antibody doesn’t happen if there is a low level or no presence of any drugs or that drug you are testing for. No colored band appears if the test is positive for drug use. When no drugs are present, the drug conjugate binds to the antibody, and the band in the test line zone becomes colored, indicating a negative result.

Urine Test Strips and Accuracy

Screening using drug test strips is quite accurate. The sensitivity levels meet National Institute on Drug Abuse (NIDA) and the Substance Abuse and Mental Health Services Administration (SAMHSA) criteria.

However, there is a risk of erroneous results due to cross-interactions with other drugs present in the urine.

Using a Professional Lab for Testing

These drug tests are very sensitive. Testing performed incorrectly will result in incorrect test results. Perform testing carefully to avoid contamination. However, at Keystone Lab, we don’t advise that you do your own testing. To get the most accurate results, hire a professional lab. Our trained professionals perform these sorts of tests all the time. Our testing lab offers regulated precautions to ensure the samples are not tampered with in some way. We believe that getting the best, most accurate results come from our testing procedures. If you are looking for employee testing or testing for any reason, reach out to Keystone Lab.  

If you are taking any prescriptions, write them down or bring them along with you. You want to disclose all medications you have taken, over the counter or otherwise.  

At Keystone, we understand how important it is to deliver the best patient care possible. Many doctors have difficulty locating their patients tailored clinical lab tests. Keystone focuses on your patients’ specific requirements so that you can deliver the best care they deserve.

Get the most accurate drug tests from the professionals. Our lab offers extensive testing of various drugs. Urine test strips are just one of the many testing options offered.

Work With A Trusted Toxicology Expert

Keystone Laboratories, a CAP-accredited North Carolina licensed laboratory and CLIA-licensed lab, is committed to helping you make important decisions that impact the safety and health of your patients with greater confidence. Clients in 48 states can get prescription drug and substance abuse recovery monitoring, specialized testing, workplace drug testing, screening, and program management services from Keystone. Contact Keystone Laboratories today to receive the industry-leading laboratory testing services!

urine test strips
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In observance of Independence Day on July 4th, Keystone will be closed. Normal office hours will resume on the 5th of July.