Short answer
Lab test terms are not just vocabulary. They shape whether a result is a screening clue, a diagnostic finding, a trend worth watching, or a number that needs confirmation in the right clinical context.
This glossary explains common words from blood tests, STI testing, genetics, microbiome reports, and emerging biomarker dashboards. It is educational, not a diagnosis or a substitute for care.
Report basics
Reference range
The high and low values a lab uses to flag many numeric results. Ranges vary by lab method, specimen, age, sex, and other factors, so compare your result with the range printed on your own report.
Abnormal flag
A label such as high, low, positive, detected, or out of range. A flag says the result needs context; it does not automatically prove a disease.
Units
The measurement scale attached to a result, such as mg/dL, ng/mL, IU/L, or copies/mL. The same marker can look very different if the units are different.
Specimen
The sample tested, such as blood, serum, plasma, urine, saliva, stool, a swab, or tissue. The right specimen matters because a negative result from the wrong body site can be misleading.
Fasting
A pre-test instruction to avoid food, and sometimes certain drinks, for a set period. Fasting can matter for some metabolic tests, but many tests do not require it.
How tests are used
Screening test
A test used to look for possible risk or disease before a diagnosis is established. A positive screen often means more evaluation is needed.
Diagnostic test
A test used to help explain symptoms, confirm or rule out a suspected condition, or classify a known problem.
Confirmatory test
A follow-up test used when a first result needs verification, a more specific method, or a different specimen type.
Reflex test
An additional test the lab automatically performs when the first result meets a predefined rule, such as adding a microscopic review after certain CBC findings.
Panel
A group of related tests ordered together. Panels can be efficient, but a broad panel may also return borderline findings that were not the original question.
Accuracy language
Sensitivity
How well a test detects what it is designed to detect. A highly sensitive test is less likely to miss the target when it is present, but timing and specimen quality still matter.
Specificity
How well a test avoids calling something positive when it is not present. A highly specific test is less likely to create a false positive.
False positive
A result that says the target was found or suggested when it is not truly present.
False negative
A result that says the target was not found even though it is truly present. Testing too early, using the wrong specimen, or low levels of the target can contribute.
Inconclusive or indeterminate
A result that is not clearly positive or negative. It often leads to repeat testing, a different method, or interpretation with other information.
Methods and result types
Qualitative result
A result reported as categories, such as positive or negative, detected or not detected, reactive or nonreactive.
Quantitative result
A result reported as a number. Blood markers, viral loads, hormone levels, and many chemistry tests are quantitative.
PCR or NAAT
Nucleic acid tests look for genetic material from a target organism or gene. PCR is one type of nucleic acid amplification method.
Culture
A method that attempts to grow an organism from a sample. Culture can be slower than molecular testing, but it may help when susceptibility testing or organism viability matters.
Antibody
A protein made by the immune system after exposure, infection, vaccination, or autoimmune activity. Antibody timing can make early negatives hard to interpret.
Antigen
A part of an organism or substance that a test is designed to detect directly.
Genetics and newer biometrics
Genetic variant
A difference in DNA sequence. A variant can be harmless, disease-associated, uncertain, or important only in a specific medical context.
Variant of uncertain significance
A genetic finding whose relationship to disease is not clear yet. It usually should not be treated like a confirmed harmful variant.
Germline versus somatic
Germline findings are inherited and may matter for family members. Somatic findings are acquired in certain cells, such as tumor cells, and may not be inherited.
Biomarker
A measurable signal related to biology or health. Useful biomarkers have a clear measurement method, clinical meaning, and decision context.
Baseline
Your usual value or pattern before a change. Baselines are often more useful when measured repeatedly under similar conditions.
Trend
The direction of results over time. A trend can be more informative than one borderline value, especially when the same lab and method are used.
Readiness or recovery score
A consumer-facing composite score, often from wearable data. These scores can summarize patterns but may not be validated as diagnostic tests.
Microbiome diversity score
A summary metric from stool sequencing or related methods. Diversity can be interesting, but consumer reports may overstate what a single score can prove about health.
When a term needs clinical context
Definitions are useful, but they do not replace the question the test was meant to answer. A term like "positive," "negative," "abnormal," "variant," or "biomarker" only becomes meaningful once you know the specimen, the method, the timeframe, and whether the result is being used for diagnosis, screening, monitoring, or family-risk counseling.
That is why a glossary should send people toward the result interpretation, reference-range, or follow-up guide rather than stand alone as the final word.
Related guides
- Blood test reference ranges
- Fasting for blood tests
- CBC blood test guide
- STI testing guide
- Chlamydia and gonorrhea testing
- Direct-to-consumer genetic testing
- Tumor genomic testing versus inherited genetic testing
- Stool culture versus PCR panels
- Recovery and readiness wearables
Sources
- MedlinePlus: How to Understand Your Lab Results
- MedlinePlus: Laboratory Tests
- MedlinePlus: What You Need to Know About Blood Testing
- FDA: Home Use Tests Glossary
- FDA: Tests Used in Clinical Care
- FDA: Nucleic Acid Based Tests
- National Human Genome Research Institute: Variant of Uncertain Significance