Practical 3 - Determination of RBC parameters

Question 1

HCT?

Answer 1

Haematocrit.

Percentage of volume of blood sample occupied by RBC

Question 2

MCV?

Answer 2

Mean Corpuscular Volume.

Hct / RBC count x 100

Question 3

MCH?

Answer 3

Mean Corpuscular Hb

Hb / RBC count

Question 4

MCHC?

Answer 4

Mean Corpuscular Hb Conc

Hb x 100/ RBC count

Question 5

What is used to do a red cell count?

Answer 5

Haematocytometer

Question 6

How is HCT measured?

Answer 6

Blood drawn up via capillary action. Centrifuged in capillary tube.

After centrifugation, blood separates into plasma at top and Red and white cells at bottom

Ratio of length of Red cell column to total length of cells and plasma is Hct

Question 7

How is Hb conc in the whole blood measured?

Answer 7

1. Hb released from RBC and converted to stable cyanmethaemoglobin.
2. Cyanmethaemoglobin then compared with standard using spectrophotometer
3. Unknown Hb conc = absorbance of test solution x conc of standard / absorbance of standard solution

Question 8

What are the normal ranges for RBC parameters?

Answer 8

MCV = 80-100fl
MCH = 26-34 pg
MCHC = 320-360 g/L

HCT: M = 40-52
F = 35 - 47