CSMLS MLT Exam key terms

The range of test results expected in a healthy reference population, usually spanning the central 95% of values and used to judge whether a patient result is normal.

A control chart plotting quality control results over time with mean and standard deviation lines, allowing technologists to detect shifts, trends, and random error visually.

A set of statistical rejection criteria applied to control results, such as 1-3s and 2-2s, that flag random or systematic error before patient results are reported.

A quality tool comparing a patient's current result with a previous value and flagging differences exceeding a set limit, which may indicate specimen mix-up, contamination, or a real clinical change.

The standard deviation expressed as a percentage of the mean, used to compare imprecision between assays or analyte concentrations independent of measurement units.

Transfer of analyte from one specimen to the next within an analyzer or pipetting system, producing falsely elevated or depressed results in the following sample.

The physiologically active fraction of calcium not bound to protein, measured in whole blood or plasma and affected by pH and specimen handling more than total calcium.

The calculated difference between measured cations and anions, commonly sodium minus chloride and bicarbonate, used to classify metabolic acidosis and detect unmeasured ions.

The difference between measured osmolality and calculated osmolality, suggesting the presence of unmeasured solutes such as alcohols, glycols, or other exogenous compounds.

A spuriously high potassium result caused by hemolysis, prolonged tourniquet use, fist clenching, or delayed separation of serum, where the true in vivo potassium is normal.

A spectrophotometric measure of free hemoglobin in a specimen, reported as a grade or concentration and used to decide whether results for affected analytes should be suppressed or commented.

A spectrophotometric estimate of bilirubin concentration in a specimen, used to flag interference with assays that rely on absorbance measurements at overlapping wavelengths.

A spectrophotometric estimate of turbidity from lipids in a specimen, used to identify samples in which light-scattering interference may distort chemistry and immunoassay results.

The standardized sequence for filling blood collection tubes during venipuncture, designed to prevent additive carryover between tubes that could alter test results.

A collection tube filled below its required volume, producing an incorrect blood-to-additive ratio that can affect coagulation and other additive-dependent test results.

The proportion of blood volume occupied by red cells, usually reported as a percentage or as a decimal fraction and used to assess anemia or polycythemia.

Mean corpuscular volume, the average red cell size in femtoliters, which classifies anemia as microcytic, normocytic, or macrocytic and guides further testing.

Red cell distribution width, a measure of variation in red cell size reported as a coefficient of variation, useful in distinguishing causes of anemia.

The percentage or absolute number of immature red cells containing residual RNA, reflecting bone marrow response and helping classify anemia as regenerative or nonregenerative.

A phenomenon in EDTA blood where platelets adhere to neutrophils, causing spuriously low automated platelet counts that resolve when blood is collected in citrate.

Aggregation of platelets in EDTA-anticoagulated blood that can falsely lower automated counts; smears and alternate anticoagulants are used to verify the true count.

Stacked, coin-like arrangement of red cells on a smear, often associated with increased plasma proteins such as fibrinogen or immunoglobulins, and distinct from true agglutination.

Clumping of particulate antigens or cells by cross-linking antibodies, the basis of many blood bank, serology, and microbiology identification tests.

A test of patient serum against reagent red cells to detect unexpected antibodies against red cell antigens before transfusion or pregnancy-related testing.

A test using anti-human globulin reagent to detect antibodies or complement bound to a patient's red cells in vivo, as in hemolytic transfusion reactions or autoimmune hemolysis.

A mismatch between forward and reverse ABO grouping or unexpected reactions, requiring investigation of clerical errors, weak subgroups, or interfering antibodies before transfusion.

The lowest antimicrobial concentration that visibly inhibits growth of a microorganism under defined conditions, used to guide susceptibility reporting and therapy.

An enzyme produced by some bacteria that hydrolyzes beta-lactam antibiotics, detected by specific tests and used to predict resistance to penicillins and related drugs.

A differential staining method that divides bacteria into gram-positive and gram-negative groups based on cell wall structure, giving rapid preliminary information from clinical specimens.

The proportion of truly affected individuals who test positive, reflecting a method's ability to detect disease when it is present.

The proportion of truly unaffected individuals who test negative, reflecting a method's ability to exclude disease when it is absent.

The probability that a positive or negative test result correctly reflects the presence or absence of disease, which depends on test performance and disease prevalence.

A false-negative or weakened serologic reaction caused by antibody excess that prevents lattice formation, resolved by diluting the specimen.

A falsely low immunoassay result at very high analyte concentrations caused by saturation of capture and detection antibodies, resolved by dilution and reassay.

The ratio of a urine specimen's density to that of water, reflecting solute concentration and helping assess hydration and renal concentrating ability.

A reagent strip with pads that change color on contact with urine, giving rapid semiquantitative results for pH, protein, glucose, blood, leukocyte esterase, and other analytes.

A rapid histology technique in which tissue is frozen, sectioned in a cryostat, and stained for intraoperative diagnosis, preserving fats and enzymes but giving less detail than paraffin sections.

Preservation of tissue by cross-linking proteins with formaldehyde solution, which maintains structure for paraffin processing but can mask antigens and requires controlled time and pH.

Infection control practices applied to all patients, including hand hygiene, gloves, gowns, and eye protection, treating blood and body fluids as potentially infectious.

A ventilated enclosure that protects the operator, the sample, and the environment through directional airflow and HEPA filtration during procedures that generate aerosols or splashes.