Hematocrit and Blood Cell Counting

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Questions and Answers

What is the purpose of sealing one end of the blood tube with clay?

To prevent contamination from external sources

To create a vacuum effect during centrifugation

To ensure proper blood sample analysis (correct)

To allow uniform mixing of blood and plasma

How long should the blood be centrifuged in a microhematocrit centrifuge?

15 minutes

10 minutes

3 minutes

5 minutes (correct)

Where should the hematocrit be measured after centrifugation?

Height of the plasma column only

Height of the blood cell column only

Combined height of blood and plasma (correct)

Total height of blood only

What is the appropriate hematocrit range for males?

0.41 - 0.51 Signup and view all the answers

Which squares are primarily counted to determine the WBC count?

The four large corner squares Signup and view all the answers

What should be done if the platelet count is found to be less than 100?

Count additional squares until reaching 100 Signup and view all the answers

What is the significance of using HPO (400x) in the procedure?

To enhance the visualization of platelets specifically Signup and view all the answers

What is done after obtaining a blood sample to prepare it for centrifugation?

Seal one end of the tube with clay Signup and view all the answers

What is the initial step in the blood sample preparation procedure?

Obtain a blood sample Signup and view all the answers

Which white blood cell type is predominantly found in peripheral blood?

Neutrophils Signup and view all the answers

What is the normal percentage range of basophils in a differential white blood cell count?

0-2% Signup and view all the answers

Which condition is NOT typically associated with an increased number of basophils?

Hormonal imbalance Signup and view all the answers

What technique can be used for counting white blood cells?

Battlement technique Signup and view all the answers

What is the role of erythrocyte indices in medicine?

To characterize anemias morphologically Signup and view all the answers

What is the normal absolute value range for lymphocytes in x 10^9/L?

1.0-3.0 x 10^9/L Signup and view all the answers

What is the recommended magnification for examining the reference values for females?

400X Signup and view all the answers

What is an important factor in ensuring accurate blood cell counting during centrifugation?

Adequate duration and speed Signup and view all the answers

What should be done with the pipette after drawing the diluting fluid?

Mix the contents vigorously Signup and view all the answers

For which age group is the reference value of red blood cells 0.31 - 0.44?

Children Signup and view all the answers

What is the lowest reference value for females regarding red blood cell count?

0.36 Signup and view all the answers

When preparing the pipette for blood cell counting, what specific mark should the diluting fluid reach?

1.01 mark Signup and view all the answers

What is the highest reference value for red blood cell count in females?

0.45 Signup and view all the answers

What type of motion should be used to mix the contents of the pipette?

Figure-of-eight motion Signup and view all the answers

What reference value range applies to red blood cell count in children?

0.31 - 0.44 Signup and view all the answers

Why is it important to understand centrifugation procedure in blood cell counting?

It ensures accurate results. Signup and view all the answers

What visual characteristic is associated with the complex observed under a microscope?

A dark blue network or filaments Signup and view all the answers

Which reagent is used in the reticulocyte count procedure?

1% new methylene blue in citrate-saline Signup and view all the answers

What is one of the major sources of error in platelet count?

Delay in sampling Signup and view all the answers

What effect does EDTA have on platelet counts?

Leads to falsely low platelet counts Signup and view all the answers

Which of the following steps is NOT part of the reticulocyte count procedure?

Counting the total number of white cells Signup and view all the answers

In the formula for platelet count, what does the constant 250 represent?

A multiplication factor for count correction Signup and view all the answers

What does the presence of leukemias do to platelet count results?

Causes falsely elevated results Signup and view all the answers

What is the effect of clumping platelets in a blood sample?

Leads to underestimation of platelet numbers Signup and view all the answers

During the reticulocyte count, how many red cells should be viewed microscopically?

1000 Signup and view all the answers

What does the Miller disk allow during the reticulocyte count procedure?

Estimation of large numbers of red cells quickly Signup and view all the answers

Where should the white blood cell (WBC) counting be performed on a smear?

On the body of the smear Signup and view all the answers

What condition is indicated by an increase in the number of neutrophils?

Bacterial infection Signup and view all the answers

What does an increased count of leukocytes suggest?

Viral infection or chronic infection Signup and view all the answers

What is typically seen in children suffering from severe eosinophilia?

Parasitic infections Signup and view all the answers

How should the first 100 WBCs be counted?

According to their maturity and cell type Signup and view all the answers

Which condition is characterized by an increase in eosinophils?

Allergic and parasitic infections Signup and view all the answers

What type of counting chamber is specifically used for WBC differential counting?

Multichannel counter Signup and view all the answers

What is the meaning of basophilia in the context of WBCs?

Increase in basophils Signup and view all the answers

Which type of infection is most commonly associated with leukocytosis?

Chronic infections such as M. tuberculosis Signup and view all the answers

Which of the following is NOT a function of eosinophils?

Fighting bacterial infections Signup and view all the answers

Study Notes

Hematocrit

Obtain a blood sample and fill the tube 3/4 full
Seal one end of the tube with clay
Centrifuge for 5 minutes at 10,000 rpm using a microhematocrit centrifuge
After centrifugation, determine the hematocrit by measuring the total height of blood and plasma, and the height of the blood cell column
Reference values:
- Male: 0.41 - 0.51
- Female: 0.36 - 0.45
- Child: 0.31 - 0.44

Blood Cell Counting

Use 400x magnification for WBC counting
Count 4 large squares (W) designated in the figure, each containing 16 smaller squares
Use LPO (100x) for Platelet counting
Count the 5 small squares (yellow) on the central large square
If the platelet count is less than 100, count more squares until it is reached
Equipment:
- Test tube
- Glass slides
- 1% new methylene blue in a diluent of Citrate-saline
  - 1 part 30 g/L sodium citrate plus 4 parts 9 g/L sodium chloride
- Miller disk (to be discussed later)

Reticulocyte Count Procedure

Mix 3 drops of reagent and blood in a test tube
Incubate at room temperature for 15 minutes
Remix
Make 2 wedge films on glass slides and air dry
View microscopically with an oil lens
Determine the percentage of immersion reticulocytes in at least 1000 red cells
A Miller disk in the eyepiece can be used to estimate large numbers of red cells
Locate a region in the “feathery” end of the smear to count the cells

WBC Counting

Count the first 100 WBC encountered
Classify them by cell type and maturation
Tally the counts using a multichannel counter/multichannel counting chamber
The bell on the multichannel counter will ring when 100 WBC are counted
This count will serve as the differential count
Counting can be done using the battlement technique or the streak method
Neutrophils predominate in the peripheral blood
There are scenarios where one cell type increases in proportion over others

WBC Differential Counts of Normal Adults

Neutrophils: 2.0-7.0 x 10^9/L, 40-75%
Lymphocytes: 1.0-3.0 x 10^9/L, 20-45%
Monocytes: 0.2-1.0 x 10^9/L, 2-10%
Eosinophils: 0.02-0.5 x 10^9/L, 1-6%
Basophils: 0.02-0.1 x 10^9/L, 0-2%

Red Blood Cell (RBC) Indices

Wintrobe introduced calculations to determine the size, Hb content, and concentration of red cells.
Erythrocyte indices help characterize anemias morphologically.
Erythrocyte indices can be calculated from the red cell count, Hb concentration, and Hct.

Key Points

Platelet count calculation: (number of cells counted/squares counted) x dilution x 250
Sources of error in Platelet count:
- Clumping of platelets
  - Initiation of platelet aggregation and clotting
  - Skin puncture technique (capillary gives twice the error than venous)
  - Delay in sampling
Falsely elevated Platelet count: leukemias
Falsely low Platelet count:
- Platelet satellitism (platelets adhere to neutrophils)
  - Caused by EDTA
Neutrophilia: indicative of bacterial infection
Leukocytosis: indicative of viral or a chronic type of infection (e.g., M. tuberculosis or Brucellosis)
Eosinophils: increased in allergic and parasitic (helminthic) infections
- Severe eosinophilia is often seen in children with parasitic infections
Basophilia: increased in chronic myelogenous leukemia or lead poisoning
Important Note about WBC counting: Do not count cells on the “feathery” edge (thin part) of the smear, only count cells on the “body” (thick part) of the smear.

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Description

This quiz covers the procedures for measuring hematocrit and blood cell counting. You'll learn about obtaining blood samples, centrifugation processes, and the reference values for hematocrit in various demographics. It also delves into the techniques used for white blood cell and platelet counting.