Drug testing is a standard procedure in regulated industries and workplace environments used to detect prohibited substances. The terminology used to report these results often differs from common language. A result is not simply “positive” or “negative” immediately. Instead, a preliminary finding is labeled “non-negative,” which acts as an intermediate status indicating that further laboratory work is required. This designation triggers mandatory confirmation steps before a final, legally defensible conclusion can be reached.
Understanding the Terminology
A “non-negative” result describes the outcome of the initial screening test, typically performed using an immunoassay (IA) technique. This first step is designed to be highly sensitive and cost-effective, quickly flagging samples that contain drug metabolites above a predetermined cutoff level. The immunoassay provides a presumptive result, meaning it indicates the possible presence of a substance but is not definitive proof. The initial screen cannot reliably identify the specific compound or accurately measure its concentration. Immunoassays use antibodies that can sometimes cross-react with structurally similar compounds, potentially leading to a false indication. A standard “negative” result means that no targeted substance was detected or that trace amounts were below the established cutoff concentration. The non-negative finding acts as a trigger, sending the sample to the next stage of rigorous analytical testing.
The Required Confirmation Testing
Following a non-negative screen, the sample must undergo mandatory confirmation testing to eliminate the possibility of a false initial result. This secondary analysis uses highly precise methods, most commonly Gas Chromatography/Mass Spectrometry (GC/MS) or Liquid Chromatography/Mass Spectrometry (LC/MS). These techniques separate the individual chemical components and identify them based on their unique molecular structure and mass. While GC/MS has historically been the gold standard, LC/MS offers advantages for molecules that are less volatile or more polar, such as many common drug metabolites. The confirmation test definitively identifies the substance and provides an accurate, quantifiable measurement of its concentration in nanograms per milliliter (ng/mL). This measurement is then compared to the regulatory cutoff levels to determine the final result.
Possible Final Test Results
Once confirmation testing is complete, the “non-negative” status is resolved, and one of three final results is assigned. The first possibility is a final “Negative” result, which occurs if the confirmation test fails to verify the substance’s presence or if the concentration falls below the mandated cutoff level.
The second outcome is a “Positive” result, meaning the confirmation test verified the substance’s identity and measured its concentration above the allowable cutoff.
The third potential outcome is a “Cancelled” or “Invalid” result. This is issued if the sample’s integrity was compromised during collection or testing. Issues include a break in the chain of custody documentation or a finding that the specimen was adulterated or substituted. An invalid result usually requires the donor to submit a new sample for testing.
The Role of the Medical Review Officer
The final step in verifying a confirmed positive result involves a licensed physician known as the Medical Review Officer (MRO). The MRO acts as an impartial gatekeeper for the accuracy and integrity of the testing process. Before a confirmed positive result is reported to the employer, the MRO contacts the individual to conduct a confidential interview. This interview provides the donor an opportunity to offer a legitimate medical explanation for the substance’s presence, such as a valid prescription for a medication like an opioid or amphetamine. If the MRO verifies the prescription and confirms the dosage is consistent with the laboratory findings, they report the test to the employer as a verified negative result. The MRO also reviews results for issues such as adulteration or substitution, ensuring all regulatory procedures are followed before the final determination is made.