How Urine Drug Tests Work

A urine drug test is a laboratory analysis of a urine sample to determine the presence of a drug or the breakdown by-products (metabolites) of the drug. Most drugs ingested by a person are eventually excreted in urine and testing the urine can determine the presence of these drugs or their metabolites. A urine drug test is usually carried out to check for the presence of illegal drugs in an individual.

Reasons for Urine Drug Tests

1. For employment purposes. Employers carry out urine tests on potential employees to reduce the chance of hiring people who may be drug abusers.
2. In professional sports, to determine whether competitors use performance-enhancing drugs or not.
3. In medical diagnosis, to determine the cause of an illness.
4. In legal situations, such as rape where it can show the use of a date rape drug.
5. Random urine tests can be carried out in an organization, a school, an agency, and the military and so on to detect drug users.
6. Urine tests are usually carried out after an incident such as an accident or crime to determine if the persons involved are drug abusers. This can also help to allocate liability.

How is a Urine Drug Test Carried Out?

1. The person to be tested provides a urine sample which is done by simply urinating into a clean container. It is advisable that this sample collection be done in an environment where the person cannot tamper with the urine sample.
2. The provided sample is then subjected to a laboratory evaluation which includes the following:
   1. An immunoassay which serves as an initial screening test. An immunoassay test measures the concentration of drugs in the urine sample by using their reactions against other substances. For instance, a certain drug or its metabolite may cause the urine to turn a red color when a particular substance is added to the urine.
   2. If the urine sample is positive in the immunoassay, the urine is subjected to a gas chromatography/mass spectrometry test as a confirmatory test.
   3. If the immunoassay is negative, the confirmatory test is usually not carried out.

Are Urine Drug Tests Effective?

No drug test is a 100% effective and urine drug testing is even more susceptible to cheating. The following are ways in which urine test results can be affected:

1. The urine sample could be switched with another person’s urine.
2. The urine sample could be diluted by drinking a lot of water. This can affect the detection of a drug by reducing its concentration in urine.
3. There are a lot of over-the-counter drugs and food ingredients that can cause a false-positive result.
4. There are specially designed drugs – called Designer drugs - used as performing-enhancing drugs in professional sports whose metabolites cannot be detected in urine.
5. There are home-made and commercially sold adulterants (called “detox” products) created specifically for manipulating urine tests which can interfere with the detection of drugs or their metabolites.
6. Urine tests can only detect ingested drugs within particular time frames which are different for different drugs.