UDT is common in employment, legal, and medical settings to check for drug metabolites. Because a positive result can have serious consequences, individuals sometimes attempt to manipulate the sample to avoid detection. These attempts usually involve introducing a foreign substance or replacing the sample entirely. Modern laboratories have developed sophisticated methods to verify the authenticity and integrity of every sample submitted. Validation checks are designed to catch the use of synthetic urine and chemical adulterants before the actual drug screening begins.
Common Methods of Sample Manipulation
Individuals typically employ three main strategies to circumvent a urine drug test. The first is substitution, which involves replacing the donor’s own urine with synthetic urine or the clean urine of another person. The challenge is maintaining the sample’s temperature and chemical profile to match a fresh human voiding.
Another common method is adulteration, where a chemical substance is added directly to a valid urine sample after collection. Substances like household bleach, soap, or specialized commercial masking agents are used to interfere with the laboratory’s immunoassay testing chemistry. The goal is to destroy or chemically alter the drug metabolites, preventing their detection.
The final strategy is dilution, which aims to lower the concentration of drug metabolites below the established cutoff levels. This can be achieved by drinking excessive fluids (in vivo dilution) or by adding water or another liquid directly to the collected sample (in vitro dilution). While dilution does not introduce fake urine or foreign chemicals, it still results in a sample that is not representative of a normal physiological state.
Laboratory Validation Checks and Indicators of Fraud
Laboratories use Specimen Validity Testing (SVT) to confirm that a sample is genuine, unadulterated human urine. This process begins immediately upon collection with a physical check of the sample’s temperature. A fresh human urine sample must register between 90°F and 100°F within four minutes of collection. A temperature outside this range indicates substitution with synthetic or stored urine.
Visual inspection is also performed for color, clarity, and unusual foam, as synthetic urine may lack the proteins that cause natural frothing. Once the sample reaches the lab, a series of chemical integrity checks measure endogenous substances found in human urine. Laboratories test for the concentration of creatinine, a waste product of muscle metabolism consistently present in human urine.
A creatinine level below 20 milligrams per deciliter is flagged as dilute, and a severely low level can indicate substitution with a liquid lacking this natural component. Labs also measure specific gravity (SG), the ratio of urine density to water density, which measures concentration. SG values outside the typical range of 1.003 to 1.030 signal either dilution or the presence of non-human liquid.
Another check involves measuring the pH level to determine acidity or alkalinity. Human urine normally falls within a pH range of 4.5 to 8.0. Extreme pH values, such as below 3.0 or above 11.0, are strong evidence of chemical adulteration with highly acidic substances like vinegar or highly alkaline substances like drain cleaner or soap.
In addition to these general parameters, laboratories specifically test for the presence of oxidizing agents. These chemicals, like nitrites, glutaraldehyde, or bleach, are common commercial adulterants designed to interfere with drug testing assays. Advanced testing may also look for uric acid and urea, primary components of real urine that are sometimes missing or inconsistent in synthetic products.
By performing these comprehensive validity tests, a laboratory can accurately categorize a sample as substituted, adulterated, or dilute, even if the drug screening is negative. The sophistication of these checks means that even high-quality synthetic products face difficulty deceiving a modern, certified laboratory.
Consequences of Submitting a Non-Valid Sample
When a laboratory determines a sample is non-valid, the result is reported to the Medical Review Officer (MRO) or ordering entity using specific terminology. The lab categorizes the sample as “adulterated” if foreign chemicals were detected, or “substituted” if creatinine and specific gravity levels are inconsistent with human urine. A “dilute” result is reported when concentrations are abnormally low, often prompting a re-test.
For employment or legal testing, a finding of “adulterated” or “substituted” is treated the same as a confirmed positive drug test result. This confirms an attempt to manipulate the testing process, which is considered a refusal to test or a failure to comply. The specific employment or legal implications depend on the organization’s policy, but they often include disciplinary action, up to termination or legal penalties.
In cases of a simple “dilute” result without other signs of tampering, a second test is usually required, sometimes under direct observation. If the recollection is also deemed invalid or substituted, it is treated as a refusal to test. The MRO determines if there is a legitimate medical explanation for an invalid result before reporting it as a refusal to the employer.