Practical 3: Exam Notes

Question 1

Define a reticulocyte

Answer 1

Juvenile rbcs which contain remnants of ribosomal RNA

Question 2

How do we stain for reticulocytes

Answer 2

Use new methylene blue to stain the RNA

Question 3

What is % reticulocyte count and absolute reticulocyte count?

Answer 3

% RC = % of retics as a fraction of rbcs

ARC = the number of reticulocytes in 1mm3 of blood

Question 4

What is the equation for ARC?

Answer 4

(% reticulocytes/100) x RBCC

Question 5

What might cause high absolute reticulocyte count?
(7)

Answer 5

Thalassaemia

Sideroblastic anaemia (body cant incorporate iron in Hb)

Blood loss

Haemolytic anaemia

Pregnancy

Pernicious anaemia or iron deficiency anaemia after treatment

Mediations

Question 6

What might cause low ARC?
(7)

Answer 6

Aplastic anaemia -> body cant make enough rbcs -> cancer etc

Exposure to radiation

Chronic infection

Untreated pernicious anaemia

Megaloblastic anaemia

Iron deficiency anaemia

Chemotherapy medications

Question 7

How do you determine ARC?

Answer 7

Miller square
- Count all the reticulocytes in the big box
- Count all the cells in the small box
- Keep doing this till you have about 115 cells counted in the small box
- Multiply small box by 9 = N

N = number if red cells counted

% Reticulocytes = Reticulocytes counted (big box)/ No of red cells counted) x 100

ARC = (% Reticulocytes/100) x RBC

Question 8

What are the normal percentages for each cell type in a differential white cell count?

Answer 8

Neutrophils: 40% to 60%
Lymphocytes: 20% to 40%
Monocytes: 2% to 8%
Eosinophils: 1% to 4%
Basophils: 0.5% to 1%
Band (young neutrophil): 0% to 3%