Manual WBC Counts

By Fred Watson,2014-04-26 19:28
7 views 0
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.


     ***Neubauer Hemacytometer


     *** 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)


     #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??


     ―Shift to Left‖

     Leukomoid Reactions

     Neutrophils Increased

     Whooping Cough;Lymphs increased


Decreased Results: Leukopenia

    Some Viral Infections Prolonged infections(bacterial);


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.


    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


Step 2.

    WBC - #NRBCS/µL = Corrected WBC

    8,000 - 661 = 7,339/µL

Platelet Counts 4


     Platelet Unopette

    (1/100 dilution in 1%ammonium


    Neubauer Hemacytometer

     Count center square


     #platelets (100)

    (1mm?) (.1mm)


     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


Reference Range: 150 450 X 10?/µL

Elevated: Thrombocytosis

    Often seen in Fe def. anemia

    and CML

    Decreased: Thrombocytopenia


     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


    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.


     Count eosinophils in all squares on both sides and average:

     #eos (32)


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

    eosinophil count?

     (70)(32) = 700/µL


    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?)


     # RBCs (200) = #RBCs/µL


Reference Range:

    male: 4.60 6.00 X 10ˆ6/µL

    female: 4.00 5.40 X 10ˆ6/µL


     Dehydration and diuretics (Relative)

     Polycythemia (rubra) vera (PV)




     Fe Deficiency

     Vit B12 Deficiency

     Chronic Bleeding

    Red Blood Cell Indices: 7

MCV (mean corpuscular volume)

     MCV = Hct. X 10


    Ex: Hct = 45

     RBC = 4.5 X 10ˆ6/µL

     MCV = 45 X 10 = 100fL


Reference Range: 80 100 fl





MCH (mean corpuscular hemoglobin)

     MCH = Hb X 10


Report this document

For any questions or suggestions please email