Plain-language definitions of the laboratory, drug testing and sexual health terms used across LabX Diagnostics — from LC-MS/MS and cut-offs to window periods and CLIA.
A drug screen that checks one sample for 12 drugs or drug classes at once. LabX offers a 12-panel test on urine or a fingerstick blood sample.
A
Accession number
A unique identifier a laboratory assigns to a sample when it is received, used to track the sample and match it to its results.
Adulterant
A substance added to a sample to try to interfere with a test. Laboratories run specimen validity checks to detect signs of tampering.
Analyte
The specific substance a laboratory test measures, such as a drug, a metabolite or a marker of infection.
Antibody
A protein the immune system makes in response to an infection. Some tests, such as the hepatitis C antibody test, look for antibodies rather than the organism itself.
Antigen
A part of a virus or bacterium that a test can detect directly, such as hepatitis B surface antigen.
At-home collection
Collecting your own sample, such as urine or a small blood sample, at home with a kit and mailing it to a laboratory for testing.
B
Benzodiazepines
A class of sedative medicines, including alprazolam, clonazepam, lorazepam and diazepam, prescribed for anxiety, seizures and sleep.
Blood-borne infection
An infection carried in the blood, such as hepatitis B, hepatitis C or syphilis. Blood testing (serology) is the standard way to test for these; hepatitis B and C cannot be found in urine.
C
Chain of custody
A documented, unbroken record of who handled a sample and when, used for forensic or legal testing. Standard at-home tests are not chain-of-custody tests.
CLIA
The Clinical Laboratory Improvement Amendments, the federal standards that clinical laboratories in the United States must meet. LabX's CLIA number is 10D2067145.
CLIA-certified laboratory
A laboratory that holds a certificate under CLIA to perform clinical testing, with inspections and quality requirements.
COLA
An independent organization that accredits clinical laboratories. LabX Diagnostic Systems is COLA-accredited (COLA 24755).
Confirmation test
A second, more specific laboratory test that identifies exactly which compound is present. LabX's confirmation measures 76 compounds by LC-MS/MS.
Creatinine
A natural waste product the kidneys excrete at a fairly steady rate. Low creatinine can indicate a very dilute urine sample.
Cross-reactivity
When a screening test reacts to a substance other than the one it is designed to detect, which can produce a presumptive positive that confirmation testing then clarifies.
Cut-off
The concentration at or above which a laboratory reports a substance as detected. A result below the cut-off is reported as negative; it does not prove none was present.
D
Definitive testing
Laboratory testing, such as LC-MS/MS, that identifies specific compounds, as opposed to presumptive screening that detects drug classes.
Detection window
The approximate period after exposure during which a substance or its metabolite can be measured. Windows vary with dose, frequency of use, metabolism and hydration.
Dilute sample
A urine sample with low creatinine and specific gravity, often from drinking a lot of fluid, which can lower drug concentrations below the cut-off.
Drug class
A group of drugs with similar chemical structure or effects, such as opioids, stimulants or benzodiazepines. Screens often detect a class rather than a single drug.
E
ETS (ethyl sulfate)
A minor metabolite of alcohol that remains measurable longer than alcohol itself, used as a marker of recent drinking.
F
False positive
A test result that indicates a substance or infection is present when it is not. Confirmation testing is used to reduce this risk.
FDA
The U.S. Food and Drug Administration, which regulates medicines, devices and many diagnostic tests.
Fingerstick
A method of collecting a small blood sample by pricking a fingertip, used for LabX's blood drug test.
H
HCV RNA
The genetic material of the hepatitis C virus. Its presence shows the virus is currently in the blood, and it is used to follow up a reactive hepatitis C antibody test.
Hepatitis B surface antigen (HBsAg)
A protein from the hepatitis B virus whose presence in blood indicates a current hepatitis B infection.
HIPAA
The Health Insurance Portability and Accountability Act, the federal law that protects the privacy and security of health information.
I
Immunoassay
A screening method that uses antibodies to detect a drug or drug class. It is fast but can cross-react with related substances.
Interactive lab report
LabX's online results view, where each tested compound and sample check can be opened to see what it is and what the cut-off means, alongside the signed PDF.
L
Laboratory director
The physician or scientist legally responsible for a clinical laboratory's testing and quality. LabX's laboratory director is Xiaohui Zhang, M.D., Ph.D.
LC-MS/MS
Liquid chromatography with tandem mass spectrometry, a laboratory technique that separates the components of a sample and identifies each compound by its mass.
Licensed physician
A medical doctor licensed to practice medicine. Always review your laboratory results and any health decision with a licensed physician or qualified healthcare provider.
Lower limit of quantitation
The lowest concentration a laboratory method can measure reliably. On LabX confirmation reports this is shown as the lower limit and acts as the reporting cut-off.
M
Medical Review Officer (MRO)
A licensed physician who reviews drug test results, including prescription information, before results are reported in many workplace programs. LabX does not currently offer MRO review; LabX results are reviewed by licensed and trained Medical Technologists.
Metabolite
A compound the body produces when it breaks down a drug. Many tests measure metabolites because they last longer or are more specific than the parent drug.
N
NAAT
Nucleic acid amplification test, a molecular method that detects the genetic material of an organism, used for chlamydia, gonorrhea and similar infections.
Negative result
A result showing the substance or infection was not detected at or above the laboratory's cut-off at the time of collection.
ng/mL
Nanograms per milliliter, the unit used to report drug concentrations in urine and blood.
Notifiable condition
An infection that laboratories are required by law to report to public health authorities, such as many sexually transmitted infections.
O
Opioids
A class of drugs that act on opioid receptors, including prescription pain medicines, heroin and fentanyl.
Oxidants
Chemicals that do not occur naturally in urine and can interfere with drug tests. Specimen validity testing checks for them.
P
Panel
A group of tests run together on one sample, such as a 12-panel drug test or an STI panel.
Parent drug
The original drug that was taken, as opposed to the metabolites the body makes from it.
PCR
Polymerase chain reaction, a laboratory method that copies and detects the genetic material (DNA or RNA) of an organism. It is one type of nucleic acid amplification test (NAAT).
pH
A measure of how acidic or alkaline a sample is. Urine outside the normal range can suggest a sample was altered.
Positive result
A result showing the substance or infection was detected at or above the laboratory's cut-off. It is not a diagnosis and should be reviewed with a licensed physician.
Presumptive result
A screening result that suggests a drug class may be present but has not been confirmed by a definitive method.
R
Reactive result
A screening result for an infection that did not rule the infection out and may need confirmation. A reactive result is not a diagnosis.
Reference range
The range of values expected in a healthy population for a given test, used to help interpret results.
Reportable range
The span of concentrations a laboratory method can report, from the lower limit to the upper limit.
Retest
Testing again, for example after a very recent exposure when an infection might not yet be detectable.
S
Screening test
A first-line test designed to detect possible positives quickly. Screens are followed by confirmation when a definitive answer is needed.
Serology
Blood testing that looks for antibodies or antigens, used for infections such as syphilis and hepatitis and to find past or latent infection.
Signed laboratory report
The official report of results released by the laboratory, available as a PDF in your LabX account.
Specific gravity
A measure of how concentrated a urine sample is. Very low specific gravity usually indicates a diluted sample.
Specimen
The sample collected for testing, such as urine or blood.
Specimen validity testing
Checks on a urine sample, such as pH, specific gravity, creatinine and oxidants, that show whether the sample is genuine and undiluted.
STI
Sexually transmitted infection, an infection passed mainly through sexual contact, such as chlamydia, gonorrhea, trichomoniasis or syphilis.
T
Tasso device
A small collection device that presses onto the upper arm and draws a small blood sample without a traditional needle draw, used for some LabX blood kits.
Toxicology
The study and laboratory measurement of drugs, medicines and other substances in the body.
Treponemal test
A syphilis test that detects antibodies specific to Treponema pallidum, used to confirm a reactive RPR screen.
Turnaround time
How long a laboratory takes to report results, counted from when the sample is received at the laboratory.
U
Urine drug test
A drug test performed on a urine sample, the most common sample type for drug screening.
V
Vantage
The at-home testing brand of LabX Diagnostics. Vantage kits are processed by LabX Diagnostic Systems in Tampa, Florida.
W
Window period
The time after an exposure before a test can reliably detect an infection. Testing during the window period can miss an infection.
Z
Z-drugs
A group of sleep medicines, such as zolpidem, that are not benzodiazepines but act on similar brain receptors.
Talk to a licensed physician. LabX Diagnostics and Vantage provide laboratory testing only. The information on this page is educational and is not medical advice, diagnosis or treatment. Always consult a licensed physician or other qualified healthcare provider about test results, symptoms or medicines, and before making any health decision. If you think you may have a medical emergency, call 911. Read our medical disclaimer.
Medical disclaimer. LabX Diagnostics and Vantage provide laboratory testing only. Test results and information on this site are for informational purposes and are not medical advice, diagnosis or treatment. Always consult a licensed physician or other qualified healthcare provider about your results and before making any health decision. If you think you may have a medical emergency, call 911. Read the full disclaimer.
