Determining blood cell parameters

Question 1

How is red cell count estimated?

Answer 1

• Dilute the blood 200x and place a layer 0.1mm thick on a special ruled haemocytometer slide
• To dilute the blood, 5 microlitres is added to 995 microlitres of HAYEM’S solution using a capillary pipette
• By counting those in a known area, the number or red cells in 1 litre of blood can be estimated
• E.g. counting the amount in 5 medium squares (volume=0.02mm^3) , and mutiplying by 10^10 to get per litre

Question 2

How is haematocrit measured?

Answer 2

Haematocrit (Hct) is the percentage of the volume of a sample of blood occupied by the red cells

• This can be measured using a centrifuge
• The blood will separate into layers
• The ratio of the length of the red cell column to the total length is haematocrit

Question 3

How is Hb concentration measured?

Answer 3

Haemoglobin concentration in the anticoagulated blood sample is measured using the HemoCue Hb 201+ system,

Question 4

How is MCV calculated?

Units?

Answer 4

Hct / RBC count x 100

fl (10^-15 l)

Question 5

How is MCH calculated?

Units?

Answer 5

(Hb x 10) / RBC count

pg (10-12 g)

Question 6

How is MCHC calculated?

Units?

Answer 6

(Hb x 100) / Hct

g/dl

Question 7

Normal MCV?

Answer 7

80 – 100 fl

Question 8

Normal MCH?

Answer 8

26 – 34 pg

Question 9

Normal MCHC?

Answer 9

32 - 36 g/dl

Question 10

Normal leukocyte count?

Answer 10

3.5 - 7.5 *10^9 /L