Automated Analyzers: Complete Blood Count & Chemistry Panels

Flashcards covering vocabulary related to automated hematology and chemistry analyzers, including prefixes/suffixes, principles of operation, cell counting, interpretation of results, types of assays, and instrument care.

Cytosis/Philia

Prefixes/suffixes meaning increased cell numbers (e.g., erythrocytosis, neutrophilia).

Penia

Suffix meaning decreased cell numbers (e.g., lymphopenia).

Macro

Prefix meaning bigger than normal (e.g., macrocytes).

Micro

Prefix meaning smaller than normal (e.g., microcytes).

Normo

Prefix meaning normal (e.g., normochromic RBC).

Poly

Prefix meaning increased (e.g., polychromic RBC).

Hypo

Prefix meaning decreased (e.g., hypochromic RBC, hypothyroid).

Hyper

Prefix meaning increased (e.g., hyperchromic, hyperthyroid).

Total Leukocyte Count

Also known as the white blood cell count (WBC).

Impedance Analyzers

Classifies cells based on their size by counting small changes in electrical current as cells impede flow through an aperture.

Laser Flow Cytometry Analyzers

Evaluates the size and density of cells using focused laser beams, classifying them based on how they scatter light.

Quantitative Buffy Coat Analysis Systems

Uses centrifugation and staining to estimate cellular elements by expanding the buffy coat layer in a specialized hematocrit tube.

Histogram

A graphical representation of cell population, showing the number and sizes of cell types present (size on X-axis, numbers on Y-axis).

Lytic Agent

Used in impedance analyzers during WBC counting to lyse platelets and RBCs, preventing them from being counted.

Mean Corpuscular Volume (MCV)

Determined by cell volume information from analyzers, providing information on the average size of red blood cells.

Impedance Analyzer Inaccuracy in Cats

Occurs due to the similarity in size of feline RBCs and platelets.

Impedance Analyzer Inaccuracy in Exotic Species

Occurs because the size of RBCs, WBCs, and thrombocytes are too similar.

Nucleated RBCs (NRBCs) Impact on Automated WBC Count

Can cause automated total leukocyte counts to be artificially high because machines count all nucleated cells; requires mathematical adjustment.

Quantitative Buffy Coat System Limitations

Provides only estimates of cell numbers and a partial differential; abnormalities may be undetected, requiring a blood smear examination.

Scatter Plot

A visual representation typically used with histograms where each dot represents a cell, indicating its characteristics.

Differential Count

The percentage of each white blood cell type composing the leukogram, providing essential information beyond the total leukocyte count.

Leuko-tic System

A manual counting system for total leukocyte counts that uses a blood diluting solution and a hemocytometer.

Hemocytometer

A specialized counting chamber used in manual cell counting methods like the Leuko-tic system.

WBC Estimation (Blood Smear)

A quality control measure performed on the differential blood smear (e.g., # WBC/high dry field x 2 ≈ # WBC x 10⁹/L).

Absolute Differential Counts

Calculated by multiplying the total leukocyte count by the percentage of each cell type (e.g., total WBC count x cell %).

Atypical Cells

Abnormal cell types (e.g., granulocytes or agranulocytes) that didn’t divide normally; usually not recorded on a report sheet if 1-2% is normal.

Photometry (Chemistry Analyzers)

The most common chemistry analysis method, utilizing a spectrophotometer to measure the amount of light transmitted through a solution.

Electrochemical Methods (ISE)

Also known as ion-selective electrode (ISE) technology, commonly used to measure electrolytes by detecting voltage differences between electrodes.

Light-Scatter Techniques

Used to measure concentrations of larger molecules (e.g., immunoglobulins, antigen-antibody complexes) by detecting the reduction of light intensity passing through a solution.

Spectrophotometer

A machine used in photometry that produces light of various wavelengths and measures the amount of light transmitted through a sample.

Absorbance (Photometry)

A photometric technique measuring how much light was absorbed by the sample, often using wet/rotor technology.

Reflectance (Photometry)

A photometric technique measuring how much light was reflected off a test substance, used by most in-house analyzers with dry/slide chemistry systems.

Beer's Law

States a direct linear relationship between the concentration of an analyte and light absorption, where color change is proportional to concentration.

Analyte

The specific substance being measured in a sample (e.g., potassium).

End Point Assay

An absorbance assay method that measures the concentration of substances after a chemical reaction reaches a stable end point, measuring the color change.

Kinetic Assay

An absorbance assay method generally used for enzyme assays, measuring reaction results at specific times after initiation without reaching a stable end point.

Enzyme Activity

Greatly inhibited by low temperatures and accelerated by high temperatures; enzymes are proteins denatured by various factors including temperature and pH.

Potentiometers

Analyzers using electrochemical methods that contain reference electrodes to interact with specific ions for concentration calculation.

Reference Electrodes

Components of potentiometers used in electrochemical methods that are designed to interact with only one type of ion.

Dry Systems (Chemistry Analyzers)

Utilize reagent-impregnated slides, pads, or cartridges (e.g., Catalyst Dx, VetTest); often use reflectance photometry with reduced reagent handling/storage concerns.

Liquid Systems (Chemistry Analyzers)

Utilize lyophilized or pre-prepared liquid reagents (e.g., Vetscan Rotor); tend to be accurate but may require more handling and storage space.

Dedicated-Use Analyzers

Most commonly utilize electrochemical methods to test for a specific substance (e.g., blood glucose monitors like AlphaTrak 2®).

Instrument Care and Maintenance

Crucial for generating reliable results, involving following manufacturer instructions, allowing for warm-up periods, and documenting procedures.