Laboratory Evaluation of WBCs

Question 1

State the reference value for WBC count

Answer 1

4500-11500/cumm

Question 2

State the reference values for a WBC differential

Answer 2

Segmented neutrophils: 50-70%
Lymphocytes: 20-40%
Monocytes: 1-10%
Eosinophils: 1-5%
Banded neutrophils: 0-6%
Basophils: 0-2%

Question 3

What is the “reverse differential” in children?

Answer 3

Segmented neutrophils: 20-40%

Lymphocytes: 50-70%

Question 4

How do you calculate the result of a manula WBC count?

Answer 4

WBCs counted x DF x VF

Question 5

State the Coulter Principle of cell counting and sizing

Answer 5

Based on the detection and measurement of changes in electrical resistance produced by a particle suspended in a conductive diluent, traversing a small aperture

Question 6

Discuss the Coulter Principle according to what is indicated by the number of pulses

Answer 6

The # of cells

Question 7

Discuss the Coulter Principle according to what is indicated by the amplitude of the electrical pulses

Answer 7

The cell volume

Question 8

Identify the 3 subpopulations of the WBC histogram

Answer 8

Lymphocytes, monocytes, granulocytes

Question 9

Why is a WBC count corrected in the presence of nRBCs?

Answer 9

nRBCs aren’t lysed w/ the addition of the diluting fluid which falsely increases the WBC count

Question 10

What is the guideline for correcting a WBC count in the presence of nRBCs?

Answer 10

if > 5 nRBCs/100 WBCs

Question 11

Define Coulter (Impedance) Principle

Answer 11

Based on the detection and measurement of changes in electrical resistance produced by a particle (cell) suspended ina conductive diluent passing through a small aperture

Question 12

Define WBC histogram

Answer 12

Provides data on average particle size, distribution of particles about the mean size, and any presence of subpopulations (in the case of a WBC histogram, lymphocytes, monocytes, granulocytes)