Drug Testing: Four Part Series
Each day we will be posting new information about the different types of drug tests available. Today’s topic is on urine analysis drug tests.
Urine Analysis (UA) is one of the most common types of drug tests administered around the country. It is the only testing method that is approved for federally-mandated drug testing. UA tests are relatively cheap and they can screen for many different drugs at one time, which is why most rehabs and detox centers utilize this method of drug testing.
Most UA tests detect the presence of a group of five street drugs referred to as the “NIDA 5”. Those drugs include marijuana, cocaine, amphetamines, PCP, and opiates. Other UA tests can detect the presence of up to nine, ten, and even twelve different types of drugs. The most common drug test besides the five panel test is the ten panel test. It tests for the “NIDA 5” along with five different prescription drugs. These drugs include: marijuana, cocaine, amphetamines, PCP, opiates, benzodiazepines (Xanax), barbiturates, methadone, propoxyphene, and methaqualone (Quaaludes).
How Urine Analysis Works
All drugs are broken down in the body in different ways. These reactions release the active compound and then gradually degrade the drug into slightly different structures, which are called metabolites. Metabolites are excreted through different bodily fluids; the most common route is through the urine. Therefore, UA drug tests can detect the presence of different metabolites associated with each drug.
Most urine analysis drug tests are conducted using a two part method. The first method is an immunoassay (IA) screening test. Immunoassays work on the principle of antigen-antibody interaction. Antibodies are chosen which will bind selectively to drugs or their metabolites. The binding is then detected using enzymes, radioisotopes, or fluorescent compounds. IA tests are a great tool for parents who are concerned that their child might be abusing drugs because they are readily available online or in stores. Most IA testing strips are inexpensive.
Example of an IA test
In a lab setting, the IA test will result in a negative or a preliminary positive. This type of drug screening is not quantitative, meaning the result is either pass or fail. If the test is negative, the lab reports it as such and usually they do conduct confirmatory testing. If the IA test yields a positive result, then the sample is tested using the Gas Chromatography and Mass Spectometry (GC/MS) test.
GC/MS testing provides identification of the molecules based on characteristic fragmentation patterns at specific retention times. This method is quantitative, meaning that the result will be a numeric value. For example, the cut-off level for the metabolites found in marijuana is typically 50 nanograms per milliliter for an immunoassay test. If the sample has less than 50 ng/ml, the result is a negative. However, if the sample has more than 50 ng/ml, it’s a preliminary positive. The lab will then use GC/MS technology to confirm the sample is a true positive using the typical cut off level of 15 ng/ml.
Drug Detection Times
Most drugs are water-soluble, meaning they are flushed out of the body relatively quickly. However, marijuana is a fat-soluble drug, meaning that it binds to the fat in the body. Marijuana will stay in the system, and therefore be detectable, for much longer than other drugs.
Pros of UA Tests
- They’re relatively inexpensive
- UA tests are not complicated to use
- These tests are non-invasive as compared to other drug tests
- UA tests can detect most drugs after recent drug use
Cons of UA Tests
- The cup used to store the sample of urine must be sterile
- Proper procedures must be followed to avoid contamination of the sample
- It can be difficult for a person to urinate for a drug test if they have a medical issue or if they have recently urinated
- These tests can be unreliable if the person has time to “flush” their system (i.e. drinking a lot of water beforehand in an attempt to water down their urine)
- People who are unmonitored during this type of test can add an adulterant to their urine or they may substitute someone else’s clean urine for the test
Specimen Validity Testing
Urine analysis drug tests are the most common form of drug testing in the USA. These tests are relatively inexpensive and non-invasive. However, they are not always reliable if someone tries to use synthetic urine or someone else’s urine in an attempt to pass. They can also, theoretically, be beaten if someone consumes large amounts of water prior to testing.
However, labs have found a way around this through Specimen Validity Testing (SVT). An SVT test will tell the lab whether the urine donor adulterated, substituted, or diluted their urine sample. The labs will check for a few different factors in determining whether the sample is legitimate or not. They will test the pH level of urine to make sure that the urine is not synthetic and that nothing has been added to the sample. Most healthy human urine falls in the pH range of 4.6 – 8. However, eating vast portions of acidic foods and consuming certain medications may influence the pH level. Certain diseases may also cause a change in the pH level.
SVT tests also detect the specific gravity of the urine. If a donor attempts to dilute either by drinking large amounts or by adding water to the sample, then the specific gravity will be affected. For example, water has the specific gravity of 1. Healthy human urine falls in the range of 1.005 – 1.030. If a donor introduces water to their specimen, the specific gravity will be off leading to a “dilute” result reported by the lab.
Creatinine levels are also checked during an SVT test. Creatinine is the breakdown product of creatine, which is an important part of muscle. Creatinine is removed from the body entirely by the kidneys. Most healthy human urine falls in the range of 500 to 2000 mg/day, but the result also depends on the donor’s age and amount of lean body mass. Creatinine levels are thrown off when a donor consumes large amounts of water prior to their urine analysis test. Therefore, creatinine levels can be a way for the lab to check if the person was attempting to dilute their sample.
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