Tales from the Haematology Clinic: RBC

Question 1

what does WBC stand for?

Answer 1

white blood cell count in a given volume of blood

Question 2

what does RBC stand for?

Answer 2

red blood cell count in a given volume of blood

Question 3

Hb?

Answer 3

haemoglobin concentration

Question 4

Hct?

Answer 4

haematocrit (packed cell volume)

Question 5

MCV? units?

Answer 5

mean cell volume (i.e. how large a cell is)
calculation:
divide total volume of red cells by number of red cells
=
Hct/RBC
units = fl

Question 6

MCH?

Answer 6

mean cell haemoglobin
=the amount of haemoglobin in a given volume of blood divided by the number of red cells in the same volume
Hb/RBC

Question 7

MCHC?

Answer 7

mean cell haemoglobin concentration
Hb/Hct

Question 8

platelet count

Answer 8

the number of platelets in a given volume of blood

Question 9

FBC?

Answer 9

=full blood count
frequently performed blood test, often requested routinely in GP surgeries and hospitals

Question 10

anaemia meaning?

Answer 10

reduction in the amount of haemoglobin in a given volume of blood, below what would be expected

Question 11

signs of anaemia?

Answer 11

Hb is reduced
RBC and Hct/PCV are usually reduced as well

Question 12

mechanisms of anaemia?

Answer 12

RBC failure of production
RBC excess loss/destruction

Question 13

microcytic?

Answer 13

RBC that is smaller than usual, also usually hypochromic (central pallor <1/3)
happens due to lower haemoglobin content and flatter cell

Question 14

normocytic?

Answer 14

normal red cell

Question 15

macrocytic?

Answer 15

usually also normochromic

Question 16

poikilocytes?

Answer 16

abnormally shaped RBC

Question 17

elevated HbA2?

Answer 17

B thalassemia trait

Question 18

difference between iron deficiency and thalassaemia?

Answer 18

MCHC is low in iron deficiency but relatively preserved in thalassaemia
RBC is low in iron deficiency but increased in thalassaemia trait
Hb electrophoresis is normal for iron deficiency but Hb A2 is raised in B-thal trait

Question 19

common causes of microcytic anaemia

Answer 19

-defect in haem synthesis
-defect in globin synthesis (thalassaemia)
this defect will be in a/b chain haemoglobin depending on type of haemoglobin

Question 20

causes of haemolytic anaemia?

Answer 20

-membrane (hereditary spherocytosis)
-haemoglobin defects (HbSS)
-cellular metabolism (G6PD deficiency)

Question 21

polychromasia?

Answer 21

bluish tinge due to cell cytoplasm
= young red cell, due to increased erythropoiesis
polychromatic cells are also larger than normal red blood cells

Question 22

normocytic anaemia?

Answer 22

recent blood loss - gastrointestinal haemorrhage, trauma
failure of production of RBC - e.g. bone marrow failure
pooling of red cells in the spleen - hypersplenism

Question 23

symptoms of sickle cell?

Answer 23

anaemia
jaundice
gallstones
among many other symptoms
e.g. vaso occlusion - bone, kidney, retina

Question 24

why do symptoms of anaemia not show in HbSS?

Answer 24

HbS is a low affinity haemoglobin

Question 25

spleen in sickle cell disease?

Answer 25

repeated occlusion of spleen leads to functional hyposplenism

Question 26

blood film of sickle cell anaemia?

Answer 26

sickle cells
boat cells
target cells
Howell-jolly bodies