RBC

Question 1

What is hematocrit or PCV ?

Answer 1

Hematocrit is the fractional volume of RBCs present in blood. It is the amount of packed red cells present after centrifugation. When blood is taken in a test tube and centrifuged the RBCs settle deon since they’re heavier than the plasma. Its a macroscopic observation.

Question 2

Uses PCV

Answer 2

PCV is a reliable index of red cell population. From the volume we can determine the mass , no. of red cells and their Hb content.

These values are essential for red cell indices that help in detecting and classifying various types of anemias.

Question 3

Normal values of PCV in males

Answer 3

Adult male - 46% (40-50)

Question 4

Normal values of PCR in females

Answer 4

Adult females :- 42% (37-47)

Question 5

Variations in PCR

Answer 5

Lower number if RBCs decrease the PCV and vice versa . In conditions such as spherocytosis ir sickle cell anemia more plasma is trapped between the cells giving a false high value of PCR.

Question 6

Rouleax formation

Answer 6

The piling of erythrocytes on each other.

Question 7

ESR

Answer 7

The piled up erythrocytes are heavier than usual hence they settle down. Thus sedimentation of erythrocytes is facilitated by rouleaux formation. The rate at which the erythrocytes settle down is known as Erythrocyte sedimentation rate.

Question 8

Conditions where rouleaux formation is seen

Answer 8

Kala-azar
Multiple myeloma
Chronic inflammatory diseases
Gamma - globulin is high and esr is high.

Question 9

Difference between pcv and esr

Answer 9

PCV - settlement of RBCs due to centrifugation.

ESR - settlement of RBCs due to gravity.

Question 10

Factors affecting ESR

Answer 10

Shape and size of RBCs
Size of rouleaux
Plasma factors
Other factors

Question 11

How does shape of RBCs affect ESR ?

Answer 11

The biconcave shape favors rouleaux formation the most.

Change in shape decreases the rouleaux formation and hence the ESR.

Therefore ESR is less in hereditary spherocytosis and sickle cell anemia.

Question 12

How does the red cell mass affect ESR ?

Answer 12

Increase in cell mass increases viscosity thus reducing ESR

Eg. in polycythemia ESR decreases and in anemia (except sickle cell) ESR increases

Question 13

How does rouleaux formation affect ESR ?

Answer 13

ESR depends on the size of the particles. Larger the rouleaux faster it’ll fall . Thus factors that increase the size of rouleaux increases the ESR.

Increase in red cell mass without change in their shape increases ESR

Question 14

Plasma factors affecting ESR (fibrinogen)

Answer 14

The fibrinogen content contributes to rouleaux formation. In normally flowing blood rouleaux formation does not occur due to the presence of negative charges on their surface. But when the fibrinogen concentration in olasma increases it neutralises these charges enabling rouleaux formation.

Globulin also contributes to rouleaux formation.

Question 15

Other plasma factors affecting ESR

Answer 15

In some pathological conditions other plasma factors called acute phase reactants can also neutralise the charges on the RBC surface.

Therefore ESR increases in acute infections and non infective inflammations.

Question 16

Examples of acute phase reactant

Answer 16

Rise of c reactive protein in plasma in acute rheumatic fever

Question 17

Rise of ESR due to globulin increase

Answer 17

In malignancies and collagen diseases ESR increases due to rise in globulin.

Question 18

Other factors increasing ESR

Answer 18

Temperature decreases viscosity thus increasing ESR

When plasma viscosity increases the ESR decreases.

Question 19

Normal values of ESR (wintrobe’s method)

Answer 19

Males - 0-9 mm/hr

Females - 0-20 mm/hr

Question 20

Westergren’s method

Answer 20

Males - 3-5 mm/hr

Females - 5-12 mm/hr

Question 21

What are the physiological variations of ESR ?

Answer 21

High during pregnancy (high fibrinogen)
High during menstrual bleeding 
High during parturition
More in females
High in newborns and infants

Question 22

Pathological variations (increase in ESR)

Answer 22

Tuberculosis 
Acute inflammations like cellulitis 
Chronic inflammations like arthritis 
Chronic infections like tonsillitis 
Malignancy
Collagen diseases like SLE 
All types of anemias except for membrane abnormalities like hereditary spherocytosis and sickle cell disease.

Question 23

Pathological variations (decrease in ESR)

Answer 23

Polycythemia 
Sickle cell anemia
Hereditary spherocytosis 
Hypofibrinogenemia
Hyperviscosity syndromes