red blood cell parameters

Question 1

three ways to obtain blood sample

Answer 1

venous sample

finger prick or heel prick test

Question 2

how do you calculate mean cell volume

Answer 2

haematocrit divided by red blood cell count

essentially total volume of RBC by the number of RBC

Question 3

how do you calculate mean cell haemoglobin

Answer 3

haemoglobin concentration divided by red blood cell count

amount of haemoglobin in a given volume of blood divided by the number of red blood cells

Question 4

how do you calculate mean cell haemoglobin concentration

Answer 4

haemoglobin concentration divided by haematocrit

(the amount of haemoglobin in a given of blood divided by the proportion of the sample represented by the red blood cells)

Question 5

what are the units for

• white blood cell count
• red blood cell count
• platelet count

Answer 5

x10^9

x 10^12

x10^9

Question 6

what are the units for

• haematocrit
• haemoglobin concentration

Answer 6

L/L or % if packed cell volume

g/L

Question 7

what are the units for

• mean cell volume
• mean cell haemoglobin
• mean cell haemoglobin concentration

Answer 7

fL

pg

g/L

Question 8

what is polycythaemia

Answer 8

too many red blood cells in circulation

hb, Hct and RBC is all elevated

Question 9

what is true polycythaemia and what are its four causes

what is psuedo polycythaemia

Answer 9

increase in the total volume of red blood cells

• blood over transfusion or doping
• appropriately increased erythropoietin
• inappropriate erythropoietin synthesis or use
• independent of erythropoietin

reduced plasma volume

Question 10

how does polycythaemia result from appropriately increased erythropoietin

Answer 10

ie at high altitude , as a result of hypoxia

action of erythropoietin is appropriately elevated

Question 11

what are examples of inappropriate use or synthesis or erythropoietin

Answer 11

when a kidney or other tumour secretes erythropoietin

when it is administered to athletes

Question 12

what is an example of polycythaemia independent of erythropoietin

Answer 12

polycythaemia vera
an intrinsic bone marrow disorder
myeloproliferative

Question 13

what can polycythaemia lead to

what can be done to treat this

Answer 13

thick blood-hyper viscosity
can cause vascular obstruction and thrombosis

blood can be removed (venesection)
drugs given to reduce bone marrow production

Question 14

what is the definition of anaemia

Answer 14

reduction in the absolute amount of haemoglobin in the blood
in comparison with a healthy subject of the same age and gender
haemoglobin concentration is reduced
RBC and Hct is also usually reduced

Question 15

what is the difference between MCH and MCHC

Answer 15

MCH is the absolute amount of haemoglobin in an individual red blood cell on average
is microcytic and macrocytic anaemias, MCH parallels with MCV

MCHC is the concentration of haemoglobin in a red cell
correlates with shape of cells
hypochromia correlates with MCHC

Question 16

what the levels of these parameters in iron deficiency anaemia

• Hb
• MCV
• MCH
• MCHC
• RBC
• Hb electrophoresis

Answer 16

normal or lower
low in proportion to Hb 
low in proportion to Hb 
low 
low 
normal

Question 17

what are the levels for these parameters in thalassaemia trait

• Hb
• MCV
• MCH
• MCHC
• RBC
• Hb electrophoresis

Answer 17

normal or mildly decreased
lower for same Hb
lower for same Hb
relatively similar
increased
HbA2 increased in beta thal trait

Question 18

why is it important to distinguish between thalassaemia trait and iron deficiency

what is another way to distinguish between them

Answer 18

to not incorrectly prescribe iron supplement
so those with thalassaemia trait can undergo genetic counselling

iron studies