Tales from the Haematology Clinic: RBC Flashcards
what does WBC stand for?
white blood cell count in a given volume of blood
what does RBC stand for?
red blood cell count in a given volume of blood
Hb?
haemoglobin concentration
Hct?
haematocrit (packed cell volume)
MCV? units?
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
MCH?
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
MCHC?
mean cell haemoglobin concentration
Hb/Hct
platelet count
the number of platelets in a given volume of blood
FBC?
=full blood count
frequently performed blood test, often requested routinely in GP surgeries and hospitals
anaemia meaning?
reduction in the amount of haemoglobin in a given volume of blood, below what would be expected
signs of anaemia?
Hb is reduced
RBC and Hct/PCV are usually reduced as well
mechanisms of anaemia?
RBC failure of production
RBC excess loss/destruction
microcytic?
RBC that is smaller than usual, also usually hypochromic (central pallor <1/3)
happens due to lower haemoglobin content and flatter cell
normocytic?
normal red cell
macrocytic?
usually also normochromic
poikilocytes?
abnormally shaped RBC
elevated HbA2?
B thalassemia trait
difference between iron deficiency and thalassaemia?
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
common causes of microcytic anaemia
-defect in haem synthesis
-defect in globin synthesis (thalassaemia)
this defect will be in a/b chain haemoglobin depending on type of haemoglobin
causes of haemolytic anaemia?
-membrane (hereditary spherocytosis)
-haemoglobin defects (HbSS)
-cellular metabolism (G6PD deficiency)
polychromasia?
bluish tinge due to cell cytoplasm
= young red cell, due to increased erythropoiesis
polychromatic cells are also larger than normal red blood cells
normocytic anaemia?
recent blood loss - gastrointestinal haemorrhage, trauma
failure of production of RBC - e.g. bone marrow failure
pooling of red cells in the spleen - hypersplenism
symptoms of sickle cell?
anaemia
jaundice
gallstones
among many other symptoms
e.g. vaso occlusion - bone, kidney, retina
why do symptoms of anaemia not show in HbSS?
HbS is a low affinity haemoglobin
spleen in sickle cell disease?
repeated occlusion of spleen leads to functional hyposplenism
blood film of sickle cell anaemia?
sickle cells
boat cells
target cells
Howell-jolly bodies
