Drug Testing Glossary

Testing process

Adulterated specimen

A specimen that contains a substance added to interfere with testing (for example an oxidising agent). Laboratories screen for adulterants and can report the specimen as adulterated.

Chain of custody

The documented, unbroken handling of a specimen from collection through transport and testing, so a result can be defended as belonging to the donor.

Confirmation test

A second, more specific analysis — typically gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS) — that identifies the exact drug or metabolite. Only a confirmed result is reported as positive.

Creatinine

A normal urine component used to judge whether a specimen is too dilute to test. Very low creatinine suggests heavy dilution; programmes set their own thresholds.

Cutoff

The concentration threshold at which a test flags a sample. Screening cutoffs are set high enough to avoid false positives from incidental exposure; confirmation uses a lower, more specific cutoff.

Detection window

The typical time after use during which a drug or metabolite remains detectable. It varies by substance, dose, frequency, specimen and the assay cutoff.

Dilute specimen

A specimen with abnormally low creatinine or specific gravity, often from heavy water intake. It is neither a positive nor a negative; programmes may treat it as negative-dilute or require a recollection.

False negative

A negative result despite use, usually because the substance had already cleared the detection window or was below the cutoff at the time of collection.

False positive

A non-negative screening result caused by something other than the target drug, such as a cross-reacting medication. Confirmation by GC-MS or LC-MS/MS resolves almost all false positives.

GC-MS

Gas chromatography-mass spectrometry, a confirmatory technique that identifies a drug or metabolite by its chemical signature.

Immunoassay

A laboratory screening method that uses antibodies to detect a drug or metabolite above a set cutoff. It is fast and inexpensive but presumptive: a non-negative screen is confirmed by a second, more specific method before being reported as positive.

Invalid specimen

A specimen that fails laboratory validity tests (creatinine, pH, specific gravity or oxidants) and cannot be reliably tested. It usually requires recollection.

LC-MS/MS

Liquid chromatography-tandem mass spectrometry, a highly specific confirmatory technique widely used for expanded and specialised drug testing.

Metabolite

The breakdown product of a drug that many tests actually detect. For example, cocaine tests target the metabolite benzoylecgonine, and cannabis tests target THC-COOH.

Panel

The set of drug classes a test screens for, described by number (for example a 5-panel or 10-panel). Larger panels add more analytes.

Post-accident testing

Testing required after a workplace accident or incident, typically within a defined time window, in safety-sensitive or regulated roles.

Random testing

Testing of employees selected at random from a pool. Required at set rates in some federally regulated programmes such as DOT.

Reasonable suspicion testing

Testing triggered by specific, documented observations of an employee (for example behaviour or performance), rather than random or pre-employment testing.

Return-to-duty testing

Testing required before an employee who tested positive can return to safety-sensitive duties, often followed by follow-up testing.

Screening test

The first-stage test (usually an immunoassay) that flags a sample when a drug or metabolite is at or above the assay cutoff. A screening result alone is not a confirmed positive.

Specific gravity

A measure of urine concentration used alongside creatinine to detect dilution. Unusually low specific gravity can flag a dilute specimen.

Split specimen

A specimen divided into two parts at collection. If a result is disputed, the donor can ask that the second part be tested by an independent laboratory.

Regulatory & programmes

CLIA

The Clinical Laboratory Improvement Amendments, the US framework that certifies laboratories. CLIA-certified labs meet federal quality standards for testing.

DOT

The US Department of Transportation, whose rules (49 CFR Part 40) govern drug and alcohol testing for safety-sensitive transportation workers such as commercial drivers.

HHS-certified laboratory

A laboratory certified under federal standards to perform workplace drug testing, including confirmatory testing and chain-of-custody procedures.

Medical Review Officer (MRO)

A licensed physician who reviews non-negative laboratory results, gives the donor the chance to document a legitimate prescription or medical explanation, and reports the verified outcome.

SAMHSA

The Substance Abuse and Mental Health Services Administration, which publishes the Mandatory Guidelines that define federal workplace drug-testing panels and cutoffs.

Specimens

Blood test

The closest proxy to active impairment, with the shortest detection windows (hours to a couple of days). Usually ordered clinically rather than for routine workplace screening.

Hair test

A test that reads roughly a 90-day history because drugs enter the hair shaft through the bloodstream as it grows. It cannot show very recent use within the first days.

Nail test

A less common alternative to hair testing that can reflect a longer history of use. Availability and standards vary by laboratory.

Saliva (oral fluid) test

A mouth-swab test that captures recent use, because parent drugs linger in oral fluid roughly as long as impairment. Common for workplace and roadside testing.

Sweat patch

A patch worn for days that collects drugs excreted in sweat. Used in some monitoring programmes; uncommon in routine employment testing.

Urine test

The most common employment drug test. It detects drug metabolites (not the parent drug) against cutoff tables, balancing cost, detection window and legal defensibility.

Related

Results explained · Panels · Lab report abbreviations · Test types · Methodology