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Manual WBC Counts

By Fred Watson,2014-04-26 19:28
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Manual WBC Counts

    Manual WBC Counts: 1

    Principle: WBC are counted in a known volume

    Of diluted blood, where RBCs have been lysed

    (hemolyzed) using an appropriate diluent.

Equipment:

     ***Neubauer Hemacytometer

     ***Unopette

     *** Microscope

Reagents (Diluents): only one is needed

     ***2% Acetic Acid (1/20 WBC unopette)

     ***1% HCl (hydrochloric acid)

     ***1/% ammonium oxalate (1/100

    Platelet unopette)

Calculation:

     #WBCs counted (dilution factor)

     (area mm?) (depth .1mm)

WBC Counts 2

    Reference (Normal) Range:

     4.5-11.5 X 10?/µL (mm? or cmm)

     (4500 11,500)

Elevated Results: Leukocytosis

     Bacterial Infections

     Predominant cells??

     Neutrophils/Granulocytes

     ―Shift to Left‖

     Leukomoid Reactions

     Neutrophils Increased

     Whooping Cough;Lymphs increased

     Leukemias

Decreased Results: Leukopenia

    Some Viral Infections Prolonged infections(bacterial);

    Neutropenia

Corrected WBC Counts: 3

Principle: Nucleated RBCs (NRBCs) cannot

    be distinguished from WBCs on automated methods or hemacytometers. If NRBCs are present, the WBC count is falsely elevated.

Formula to correct WBC count:

     Corrected WBC = 100 X WBC

     100 + NRBC

    This correction is done if 5 or more NRBCs are seen while doing the WBC differential. (NRBCs counted in fields as diff is done; are not included in differential count.) This criteria may vary with clinical locations.

Example:

    WBC count = 8,000/µL

    NRBCs = 9

Corrected WBC = 8,000 X 100 = 7,339/µL

     100 + 9

    Absolute #NRBCs = 8,000-7,339 = 661/µL

Alternate Method:

Step 1.

    #NRBCs/µL = #NRBCs X WBC

     100 + NRBCs

    9 X 8,000/µL = 661/µL

     109

Step 2.

    WBC - #NRBCS/µL = Corrected WBC

    8,000 - 661 = 7,339/µL

Platelet Counts 4

Equipment:

     Platelet Unopette

    (1/100 dilution in 1%ammonium

    oxalate)

    Neubauer Hemacytometer

     Count center square

Calculation:

     #platelets (100)

    (1mm?) (.1mm)

Example:

     You counted 290 platelets on one side of the hemacytometer, and 310 platelets on the other side.

    What is the platelet count? Average the two sides: 290 + 310 = 600/2

     (300) (100) = 300,000/µL

     (1mm?)(.1mm)

Reference Range: 150 450 X 10?/µL

Elevated: Thrombocytosis

    Often seen in Fe def. anemia

    and CML

    Decreased: Thrombocytopenia

     DIC

     Autoimmune platelet disease

     Acute leukemias

    Old Counting Method: Rees-Ecker

     Stain platelets with Rees-Ecker and dilute 1/200

    Also must test Platelet Function:

    1. Adhesion

    2. Aggregation

    3. release reaction (secrete platelet

    contents)

    4. clot retraction

Eosinophil Counts 5

Fuchs-Rosenthal Counting Chamber

    Dimensions: 4mm X 4 mm X 0.2mm

     Total area: 16mm?

     Depth: 0.2 mm

    Eosinophil Unopette: 1/32 dilution with

    stain for eosinophils.

    Procedure:

     Count eosinophils in all squares on both sides and average:

     #eos (32)

     (16mm?)(0.2mm)

     Example: On one side you count 65 eos and 75 on the other side. What is the

    eosinophil count?

     (70)(32) = 700/µL

     (16mm?)(.2mm)

    Reference Range: 0 -400/µL

RBC Manual Counts 6

     (No longer considered accurate/some books do not cover)

Diluent: Must be isotonic. Why?

     (not hypotonic or hypertonic)

     Isotonic saline: 0.85%(w/v) 1.

    How would you make up

    100 ml?

    2. Isoton (Coulter Counter product)

    3. Dacie’s fluid

     Gower’s solution 4.

    Dilute 1/200

    Within the center square, count 5 small squares (4 corner squares and center) Total area = 5/25mm? (0.2mm?)

Calculation:

     # RBCs (200) = #RBCs/µL

     (0.2mm?)(0.1mm)

Reference Range:

    male: 4.60 6.00 X 10ˆ6/µL

    female: 4.00 5.40 X 10ˆ6/µL

Elevated:

     Dehydration and diuretics (Relative)

     Polycythemia (rubra) vera (PV)

Decreased:

     Anemias:

     Hemolytic

     Fe Deficiency

     Vit B12 Deficiency

     Chronic Bleeding

    Red Blood Cell Indices: 7

MCV (mean corpuscular volume)

     MCV = Hct. X 10

     RBC

    Ex: Hct = 45

     RBC = 4.5 X 10ˆ6/µL

     MCV = 45 X 10 = 100fL

     4.5

Reference Range: 80 100 fl

    Interpretation:

     Normocytic

     Microcytic

     Macrocytic

MCH (mean corpuscular hemoglobin)

     MCH = Hb X 10

     RBC

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