Product Intelligence by Katriona Scoffi n H
powered by
Hematology Analyzers—From Complete Blood Counts to Cell Morphology
ematology analyzers are used widely in patient and research settings to count and characterize blood cells for disease detec- tion and monitoring. Basic analyzers return a complete blood count (CBC) with a three-part diff erential white blood cell (WBC) count. Sophisticated analyzers measure cell morphology and can detect small cell populations to diagnose rare blood conditions.
Hematology analyzer technology The three main physical technologies used in hematology analyzers are:
electrical impedance, fl ow cytometry, and fl uorescent fl ow cytometry. These are used in combination with chemical reagents that lyse or alter blood cells to extend the measurable parameters. For example, electrical impedance can diff erentiate red blood cells (RBCs), WBCs, and platelets by volume. Adding a nucleating agent that shrinks lymphocytes more than other WBCs makes it possible to diff erentiate lymphocytes by volume.
Electrical impedance The traditional method for counting cells is electrical impedance, also known as the Coulter Principle. It is used in almost every hematology analyzer.
about the morphology of blood cells. It is an excellent method for deter- mining fi ve-part WBC diff erentials.
A single-cell stream passes through a laser beam. The absorbance is mea- sured, and the scattered light is measured at multiple angles to determine the cell’s granularity, diameter, and inner complexity. These are the same cell morphology characteristics that can be determined manually from a slide.
Fluorescent fl ow cytometry Adding fl uorescent reagents extends the use of fl ow cytometry to mea- sure specifi c cell populations. Fluorescent dyes reveal the nucleus-plasma ratio of each stained cell. It is useful for the analysis of platelets, nucleated RBCs, and reticulocytes.
Proprietary technologies Manufacturers combine these three technologies with innovative uses of reagents, hydrofl uidics, and data analysis tools to produce proprietary
Whole blood is passed between two electrodes through an aperture so nar- row that only one cell can pass through at a time. The impedance changes as a cell passes through. The change in impedance is proportional to cell volume, resulting in a cell count and measure of volume.
Impedance analysis returns CBCs and three-part WBC diff erentials (granulocytes, lymphocytes, and monocytes) but cannot distinguish between the similarly sized granular leukocytes: eosinophils, basophils, and neutrophils.
Counting rates of up to 10,000 cells per second can be achieved and a typical impedance analysis can be carried out in less than a minute.
Flow cytometry Laser fl ow cytometry is more expensive than impedance analysis, due to the requirement for expensive reagents, but returns detailed information
Your choice of instrument will be driven primarily by the setting of use: patient bedside, consulting room, clinical lab, or research lab.
methods, each of which has strengths in terms of accuracy, speed, or breadth of parameters.
Siemen’s (www.healthcare.
siemens.com) ADVIA® in- struments use peroxidase staining for diff erential test-
ing. This provides a secondary total WBC that acts as an internal QC check.
The Sysmex (
www.sysmex.com) sodium lauryl sulfate method for hemo- globin analysis is a noncyanide method with very short reaction times. Hemoglobin is determined in a separate channel, minimizing interference from high leukocyte concentrations.
The Abbott (
www.abbottdiagnostics.com) CELL-DYN Sapphire® uses three-color fl uorescence combined with patented MultiAngle Polarized Scatter Separation technology to deliver accurate WBC enumeration and identifi cation using four angles of light scatter.
What to consider when buying a hematology analyzer Your choice of instrument will be driven primarily by the setting of use:
patient bedside, consulting room, clinical lab, or research lab. Note that AMERICAN LABORATORY • 26 • JUNE/JULY 2014
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64