Page 640 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

624 PART 8 ■ Fundamentals of Hematological Analysis

WHOLE BLOOD CELL ANALYSIS
TABLE 30.1 Calculated Output

Clinical laboratory automation has been evolving rapidly

during the past 40 years. A signi cant innovation is auto- Type Hematocrit RDW MCV

mated ront-end (preanalytical [preexamination]) instru-

mentation/robotics and total work cells linked by a track or Beckman RBC × MCV CV% of RBC Mean of RBC

conveyor. Because specimen processing is perhaps the most Coulter histogram size distribution

labor-intensive portion o the testing process, automating histogram

this preanalytical (preexamination) process is one option or Abbott RBC × MCV Relative Mean of RBC

streamlining procedures to reach maximum e ciency and to value to CV size distribution

improve customer service. T e critical workload volume to histogram

reach to invest in ront-end automation is between 1,500 and Sysmex Mean pulse RDW-SD (fL) Hct/RBC

2,000 specimens per day. Bayer RBC × MCV CV% Mean of RBC

Automated analyzers now orm the backbone o clinical volume histogram

laboratories both large and small. Smaller analyzers are com-
,
monly used in S A labs, reestanding clinics, physicians’ RDW, red cell distribution width; MCV mean corpuscular volume; RBC, red
,
o ces, and small hospital laboratories. Larger and more blood cell; CV coef cient of variation; RDW-SD, red cell distribution width
based on standard deviation; Hct, hematocrit.
complex systems are used in larger clinical and research

laboratories.

T e degree o instrumental sophistication is requently capabilities continue to be developed. Some o the innova-

described by the number o parameters that the instrument tions include the ollowing:

generates. T e term parameter is a statistical term that re ers

to any numerical value that describes an entire population. ■ Quantitation o nucleated erythrocyte (NRBC) counts

Parameter should be clearly distinguished rom the term ■ A channel or enumeration o immature granulocytes

sample, which is a subset o a population. Any numerical (IGs)

value describing a sample is called a statistic. ■ Random access CD4 lymphocyte counting

Te smaller hematology instruments measure erythro- ■ Analysis or CD34, CD38, and CD61 cell markers

cytes (RBCs), leukocytes (WBCs), and platelets. Entry-level ■ Measurement o reticulocyte hemoglobin

hematology instruments generate eight measured or calcu- ■ Enumeration o hematopoietic progenitor cells (HPCs)

lated parameters (WBC, RBC, hemoglobin [Hgb], hema- ■ Counting o IGs

tocrit [Hct], MCV, mean corpuscular hemoglobin [MCH],

mean corpuscular hemoglobin concentration [MCHC], and Types of Automated Cell Counting

platelets). Computerized systems generally f ag high or low Instruments

patient results. T ese systems are automated rom sample

aspiration through result printout (Fig. 30.7). Additional Major types o automation are representative o the ways

basic parameters include erythrocyte morphology in or- that blood cells can be counted, leukocytes di erentiated,

mation expressed as red cell distribution width (RDW), Mean and other components (e.g., MCH and MCHC) calculated.

Platelet Volume (MPV), or leukocyte histogram di erential. Hemoglobin is measured by the traditional cyanmethemo-

Other calculated output is expressed di erently, depending globin ow-cell method at 525 and 546 nm, depending on

on the manu acturer ( able 30.1). the instrument manu acturer. Models and eatures o instru-

echnology continues to deliver new automation capa- mentation change rapidly. T e reader is advised to re er to

bilities in hematology. For example, automated reticulocyte the respective manu acturers’ Web sites or any updates.

counting was a leading edge technology a ew years ago but Exam ples of Autom ated Instrum ents

is a routinely measured parameter in many clinical laborato-

ries today. Some o the latest instruments prepare and stain CELL-DYN Series (http://www.abbott.com )

peripheral blood smears and automatically correct or leu- Te basic system uses multiangle polarized scatter separation

kocyte (WBC) inter erence. Newly developed instrumental (MAPSS) f ow cytometry with hydrodynamic ocusing o the

FIGURE 30.7 Sysmex lavender top hematology and diabetes testing solution. (Courtesy o Sysmex America, Inc.)