CLT8 key terms

The standardized sequence in which blood collection tubes are filled during venipuncture, arranged so that additive carryover between tubes does not alter results; culture, coagulation, and additive-free tubes precede those with additives.

Transfer of a tube's additive, such as EDTA or citrate, into the next tube drawn through a shared needle holder, potentially causing falsely low calcium or prolonged clotting times in the affected specimen.

Duration the constricting band remains applied during phlebotomy; exceeding about one minute concentrates proteins and cells and raises potassium, so prolonged application should be released before filling later tubes.

Rupture of red blood cells releasing hemoglobin and intracellular contents into plasma or serum, falsely elevating potassium, lactate dehydrogenase, and aspartate aminotransferase while interfering with many photometric measurements.

Predefined conditions under which a laboratory declines to test a sample, such as unlabeled or mislabeled containers, gross hemolysis, insufficient volume, clotted anticoagulated blood, or improper transport temperature.

Presence of ethylenediaminetetraacetic acid in a specimen drawn for chemistry or coagulation testing, producing falsely low calcium and magnesium and invalid clotting results by chelating divalent cations.

A control chart plotting quality control results over time against a mean and standard deviation lines, allowing visual detection of shifts, trends, and random error in an analytical system.

A set of statistical rejection criteria, including 1-2s warning and 1-3s, 2-2s, R-4s, and 4-1s rejection rules, applied to control data to distinguish random from systematic analytical error.

A peer-comparison metric expressing how far a laboratory's result lies from the method group mean in standard deviation units; values beyond plus or minus two usually prompt investigation.

External program in which unknown specimens are analyzed and results compared with peer laboratories or reference values, used to verify ongoing analytical accuracy and required for accreditation.

Documented process establishing that an analytical procedure is suitable for its intended use, covering accuracy, precision, analytical sensitivity, reportable range, interference, and reference intervals before patient testing begins.

The range of values, typically spanning the central 95 percent of a healthy population, used to interpret whether a patient result is expected or abnormal for that analyte.

The smallest analyte concentration that can be reliably distinguished from zero, often expressed as the limit of detection or limit of quantification of a measurement procedure.

The relationship stating that absorbance is proportional to analyte concentration, path length, and molar absorptivity, forming the basis of photometric measurement in clinical chemistry analyzers.

Measurement technique in which light of a selected wavelength passes through a sample and the absorbed fraction is used to quantify concentration, commonly applied to enzymes, substrates, and colored reaction products.

Analytical method measuring light scattered at an angle by antigen-antibody complexes or particles in suspension, widely used for quantifying immunoglobulins, complement, and specific proteins.

Measurement of light blocked or attenuated by suspended particles in a solution, used to quantify precipitation reactions and immunoassays at higher analyte concentrations.

False-negative or falsely low immunoassay result caused by excess antibody in the sample saturating antigen binding sites, preventing lattice formation; resolved by diluting the specimen and retesting.

Falsely low result in a two-site immunometric assay when extremely high antigen concentrations saturate both capture and detection antibodies, preventing sandwich formation; dilution reveals the true value.

Calculated difference between measured cations and anions, usually sodium minus chloride and bicarbonate, used to classify metabolic acidosis and detect laboratory error or unmeasured ions.

Difference between measured osmolality and calculated osmolality; an elevated gap suggests unmeasured osmotically active substances such as ethanol, methanol, ethylene glycol, or isopropanol.

Comparison of a current patient result with a previous value from the same individual to flag unexpectedly large changes that may indicate specimen mix-up, mislabeling, or a genuine clinical change.

Rules-based software process that releases results meeting predefined criteria without manual review, while holding out-of-range, delta-check-flagged, or otherwise questionable results for technologist inspection.

Panel of hematology measurements including red cell count, hemoglobin, hematocrit, red cell indices, white cell count with differential, and platelet count, used to assess blood cell disorders.

Average volume of a red blood cell, derived from hematocrit divided by red cell count, used to classify anemia as microcytic, normocytic, or macrocytic.

Percentage or absolute number of immature red cells containing residual RNA, reflecting bone marrow erythropoietic response and helping distinguish decreased production from increased destruction or loss.

Prothrombin time result standardized against a thromboplastin reference preparation, allowing comparison across reagent lots and laboratories, chiefly for monitoring oral vitamin K antagonist therapy.

Clotting test that activates the intrinsic and common pathways, used to screen for factor deficiencies, monitor unfractionated heparin, and investigate prolonged bleeding or preoperative hemostasis.

Ability of platelets to adhere, activate, and aggregate at sites of vascular injury, assessed by aggregation studies or closure time and affected by drugs such as aspirin and clopidogrel.

A viable microbial cell or group of cells that grows into a single visible colony on solid medium, forming the basis for quantifying organisms as colony-forming units per milliliter.

Differential staining procedure that divides bacteria into gram-positive and gram-negative groups based on cell wall structure, providing rapid presumptive information from clinical specimens and cultures.

Lowest antimicrobial concentration that visibly inhibits growth of an isolate under defined conditions, interpreted against breakpoints to categorize the organism as susceptible, intermediate, or resistant.

Coordinated program promoting appropriate antimicrobial selection, dose, duration, and de-escalation, supported by laboratory susceptibility reporting and rapid diagnostics to limit resistance emergence.

Isolation of organisms such as coagulase-negative staphylococci or diphtheroids from blood cultures that usually represent skin flora introduced during collection rather than true bloodstream infection.

Sensitivity is the proportion of truly diseased persons correctly identified as positive; specificity is the proportion of truly non-diseased persons correctly identified as negative by a test.

Probability that a person with a positive test result actually has the condition, dependent on both test performance and the prevalence of the disease in the tested population.

Second, usually more specific assay performed after a reactive screening result to establish or exclude a diagnosis, reducing false positives before results are reported to clinicians.

Ratio of urine density to that of water, reflecting the kidney's ability to concentrate or dilute urine; measured by refractometry, reagent strip, or harmonic oscillation.

Examination of centrifuged urine sediment for cells, casts, crystals, bacteria, and other formed elements, used to evaluate renal and urinary tract disease.

Alteration of a dipstick result by substances or conditions other than the analyte, such as ascorbic acid causing false-negative glucose or blood, or high specific gravity affecting pH readings.

Infection control practices applied to all patients regardless of diagnosis, including hand hygiene, gloves, gowns, masks, eye protection, and safe handling of sharps and contaminated materials.

Graded classification of laboratory containment requirements, from BSL-1 through BSL-4, specifying facility design, equipment, and practices appropriate to the risk of the agents handled.

Accidental percutaneous exposure to a needle or other sharp device, requiring immediate washing, reporting, source evaluation, and post-exposure prophylaxis assessment for bloodborne pathogens.