CBC Parameters and QC

7/28/2019 CBC Parameters and QC

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Automated CBC ParametersandQuality Control

Joanna Ellis, MLS(ASCP)


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The Automated

Complete Blood Count Most common test in the Hematology lab.

Main Components of the CBC: Cell counts

Hgb

RBC indices

WBC differential absolute values and percent

Indications for CBC: Fatigue

Weakness Infection

Inflammation

Bruising

Bleeding


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CBC Parameters

PARAMETER UNIT OF REPORTING COMMON METHOD OF DETERMINATION

WBC X 103 /L Impedance count X calibration (cal) factor

RBC X 106 /L Impedance count X calibration factor

HGB g/dL Colorimetric absorbance in proportion to hemoglobin

MCV fL

From RBC histogram,

#of RBCs X size of RBCs X cal constant OR Calculated: HCT X 10RBC

HCT %Calculated: RBC X MCV

10

MCH PgCalculated: HGB X 10

RBC

MCHC g/dL or % Calculated: HGB X 100HCT

RDW % Impedance (from histogram)

Platelet X 103 /L Impedance count X cal factor

WBC DiffAbsolute: X103 /L

Percent of WBC : %Light Scatter , flow cytometry


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M77221


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CBC

Adult Reference RangesParameter Adult Reference Range

WBC 4.5-11.0 X 103/L

RBCMale: 4.5-5.5 X 106 /L

Female: 4.0-5.0 X 106 /L

HGBMale: 14-17.4 g/dL

Female: 12.0-16.0 g/dL

HCTMale: 42-52%

Female: 36-46%

MCV 80-100 fl

MCH 28-34 pg

MCHC 32-36 g/dL or %

RDW 12.0-14.6%

PLT 150-450 X 103 /L

MPV 6.8-10.2 fl


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Linearity

(Reportable Range)

Instruments are calibrated for each analyte with arange that is clinically relevant.

With concentrations above or below thereportable range or Linearity range, the resultdoes not correspond with the calibration curve inlinear fashion.

Results outside of linearity are NOT acceptable. Linearity ranges vary by instrument.

Example: Parameter Coulter STKS Advia

WBC 0.0 -99.9 X 103

/L 0.02-400 X 103

/L


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Advia

Linearity Instrument Codes

Code Cause Action Indicated

+++++Result exceeds reportable

range

Dilute 1:2 and rerun.

Continue further dilutions

until result is within linearity

H

Result higher than the

laboratory set patient high

action limit

Review Result

L

Result is lower than the

laboratory set patient low

action limit

Review Result


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CBC Quality Control Commercial Controls:

3 levels (low, normal, high)

Values stored in instrument computer

Levey-Jennings graph generated and stored for each parameter

Mode to Mode QC:

Most automated hematology instruments have a primary andsecondary mode of sample aspiration. Controls must be run onBOTH and correlate.

Primary=Automated or Closed

Secondary=Manual or Open

Delta Checks

When the Laboratory Information System (LIS) and the instrumentare interfaced (connected) delta checks are conducted by the LISon select parameters.

Current values compared to most previous result

Differences greater than the limits set within the LIS are

flagged


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WBC Parameter

Interfering substances and Implications

Test Name Interfering Agent Clinical Implications

WBC

White

Blood

Cell

Count

Unusual RBC abnormalities that

resist lysis

Nucleated RBCs

Fragmented WBCs

Unlysed particles greater than 35 fL

Very large or aggregated pltsSpecimens containing fibrin, cell

fragments or other debris (esp

pediatric/oncology specimens

LOW 11.0 X103 /L

Infections

Inflammation

cancer, leukemia
http://www.labtestsonline.org/understanding/conditions/autoimmune.htmlhttp://www.labtestsonline.org/understanding/conditions/leukemia.htmlhttp://www.labtestsonline.org/understanding/conditions/leukemia.htmlhttp://www.labtestsonline.org/understanding/conditions/autoimmune.html


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RBC Parameter



RBC

Red

Blood

CellCount

Very high WBC count (greater than 99.9)

High concentration of very large platelets

Agglutinated RBCs, rouleaux will break up

when Istoton is added

RBCs smaller than 36 fLSpecimens containing fibrin, cell fragments or

other debris (esp pediatric/oncology specimens

LOW:Male: < 4.5 X 106 /L

Female: < 4.0 X 106 /L

Anemia

HIGH:

Male: > 5.5 X 106 /LFemale: > 5.0 X 106 /L

Polycythemia vera,

fluid loss due to

diarrhea, dehydration,

buns
http://www.labtestsonline.org/understanding/conditions/diarrhea.htmlhttp://www.labtestsonline.org/understanding/conditions/diarrhea.html


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HGB Parameter



HGB

Or

Hb

Hemoglobin

Very high WBC count

Severe lipemia

Heparin

Certain unusual RBC abnormalities

that resist lysing

Anything that increases the turbidity

of the sample such as elevated levels

of triglycerides

High bilirubin

LOW:

Male: 16.0 g/dL

Polycythemia vera

fluid loss due to diarrhea,

dehydration, burns
http://www.labtestsonline.org/understanding/conditions/diarrhea.htmlhttp://www.labtestsonline.org/understanding/conditions/diarrhea.html


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HCT Parameter



HCT Hematocrit

Known factors that interfere with the

parameters used for computation, RBCand MCV

LOW:

Male:


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MCV Parameter



MCV

Mean

Corpuscular

(Cell)

Volume

Very high WBC count

High concentration of very large

platelets

Agglutinated RBCs

RBC fragments that fall below the 36 fL

threshold

Rigid RBCs

LOW: 100 fL

B12

Folate Deficiency


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RDW Parameter



RDW

Red Cell

DistributionWidth

Very high WBC

High concentration of very large or

clumped platelets

RBCs below the 36 fL threshold

Two distinct populations of RBCs

RBC agglutinates

Rigid RBCs

HIGH: >14.6%

Mixed population of RBCs

Immature RBCs tend to

be larger


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WBC Differential Parameters

Clinical Implications in Adults

Test Name Clinical Implications of

LOW %

Clinical Implications of HIGH %

Neut % Neutrophil %

In 100 WBC

differential

LOW: 80%

Bacterial infection

Inflammatory disease

Chronic myelogenous leukemia

Lymph % Lymphocyte % LOW: 35%

Viral infectionChronic or Acute Lymphocytic Leukemia

Mono % Monocyte % LOW: 10%

Inflammatory disorders

Myelomonocytic leukemia

Eos % Eosinophil % HIGH: >5%

Parasitic infection

Allergic reaction

Baso % Basophil % HIGH: >1%

Allergic reaction to food

Chronic inflammation
http://www.labtestsonline.org/understanding/conditions/lupus.htmlhttp://www.labtestsonline.org/understanding/conditions/hiv.htmlhttp://www.labtestsonline.org/understanding/conditions/hiv.htmlhttp://www.labtestsonline.org/understanding/conditions/lupus.html


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References

Harmening., Denise, Clinical Hematology and Fundamentals of

Hemostasis, 3rd edition, pp. 593-599.

Turgeon, Mary Louise, Clinical Hematology - Theories and Procedures,

3rd edition, pp373, 376-382.

Rodak, Bernadette, Diagnostic Hematology, 1st edition, p.605-606.

Coulter STKS Operating Manual

McKenzie, Shirlyn, Clinical Laboratory Hematology, 2nd edition,pp813-829.

"Complete Blood Count: The Test." Lab Tests Online: Welcome!

American Association for Clinical Chemistry, 18 June 2010.

Web. 13 Sept. 2010.

.

"WBC Differential Count: The Test." Lab Tests Online: Welcome! American

Association for Clinical Chemistry, 18 June 2010. Web. 13 Sept.

2010.http://www.labtestsonline.org/understanding/analytes/dif

ferential/test.html#what>.

CBC Parameters and QC

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