Drug testing is a routine part of many environments, from employment screenings to athletic competitions. While a “negative” result means no substances were detected, the concept of a “non-negative” result is often less clear. This term encompasses a range of outcomes more nuanced than a simple “positive,” requiring further evaluation.
Defining “Non-Negative” Drug Test Results
A “non-negative” drug test result is an umbrella term, indicating a sample does not meet the criteria for a clear negative finding. This can point to the presence of a substance, an integrity issue with the sample, or an attempt to interfere with the testing process. Several specific categories fall under this classification, each with distinct implications.
A “positive” result means specific drug metabolites were detected in the sample at concentrations exceeding a predetermined cut-off level. For instance, a positive test for cannabis metabolites indicates THC-COOH above a threshold, typically 15 ng/mL for confirmation, following an initial screening cut-off of 50 ng/mL. These cut-off levels differentiate between actual drug use and incidental exposure.
A test result can also be deemed “invalid,” signifying an issue with the sample that prevents a definitive determination. This might occur if the sample’s pH or specific gravity falls outside the acceptable range. Such deviations suggest a problem with the sample’s composition, making it unreliable for accurate drug detection.
When a sample is classified as “substituted,” it means the submitted specimen is not consistent with human urine. This indicates a deliberate attempt to defraud the test, perhaps by using synthetic urine or a sample from another source. Laboratory analysis detects this by identifying creatinine levels and specific gravity inconsistent with human biological fluids.
An “adulterated” result indicates a foreign substance was added to the urine sample with intent to interfere with the test’s outcome. Common adulterants include oxidizing agents or other chemicals that can degrade drug metabolites or interfere with the immunoassay’s chemical reactions. These substances are detected through specific integrity tests.
A “diluted” result occurs when the urine sample has abnormally high water content, potentially masking the presence of drugs. This is identified by low creatinine concentration and low specific gravity. While sometimes due to excessive fluid intake, it can also be an attempt to obscure drug use and may necessitate a retest.
What Happens After a Non-Negative Result?
Following an initial non-negative screening result, particularly a presumptive positive, the sample undergoes a more precise laboratory process: confirmation testing. This stage employs highly accurate analytical techniques, such as Gas Chromatography-Mass Spectrometry (GC-MS) or Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS). These methods precisely identify and quantify specific drug metabolites, providing definitive proof of their existence and concentration.
Once confirmation testing is complete, the information is forwarded to a Medical Review Officer (MRO). The MRO is a licensed physician with specialized knowledge of substance abuse disorders and drug testing protocols. The MRO’s role involves reviewing all laboratory results, including any integrity issues, and contacting the individual to discuss potential legitimate medical explanations for detected substances.
During this conversation, the MRO will inquire about any valid prescriptions or other medical reasons that might explain the confirmed positive result. This confidential discussion ensures individuals with legitimate medical conditions are not unfairly penalized. The MRO also evaluates any documentation provided by the individual, such as prescription records, to corroborate their explanation.
After reviewing all available information, the MRO makes a final determination regarding the test result. This final determination could be a confirmed positive, a negative with a legitimate medical explanation, a refusal to test if the individual fails to cooperate, or a canceled test due to laboratory error. For samples initially flagged as diluted, the MRO might recommend a retest, depending on the specific drug testing policy.