Week 1- Introduction to anaemia and microcytic anaemias Flashcards
What is anaemia?
Reduced total red cell mass.
What markers are used to measure anaemia?
Haemoglobin and haematocrit are used as surrogate markers. However this assumes that haemoglobin mass equals red cell mass. Also assumes that there is a steady state in blood volume (haematocrit measures the proportion of red cells in total blood vol)
What should the adult male haemoglobin be?
<130g/L
What should the adult female haemoglobin be?
<120g/L
What should the adult male haematocrit be?
0.38-0.52
What should the adult female haematocrit be?
0.37-0.47
Where does red cell production take place?
Bone marrow
How would you measure haemoglobin using a spectrophotometric method?
Burst (lyse) the red cells to create a Hb solution
Stabilise the Hb molecules (cyan-met Hb)
Measure the optical density (this is how red the cells are)
Optical density is proportional to the density (Beers Law)
Hb concentration worked out using known reference standard cyan-met Hb.
How do you measure haematocrit? How do modern machines differ?
Ratio of the blood that is red cells if the blood was left to settle. Modern machines now by adding a calculated volume of the red cells it counts.
In what cases are haematocrit or haemoglobin not good markers of anaemia?
When someone becomes acutely unwell and loses blood, the total volume of blood reduces however the haemoglobin concentration will remain the same and so will the percentage of blood that is red cells.
Also in haemodilution. Plasma volume expands in pregnancy and therefore the haemoglobin concentration is reduced.
What is a reticulocyte?
Red cells that have just left the bone marrow, they are larger than normal red cells. It still has some traces of dark blue/purple RNA.
How does the body respond to anaemia?
Reticulocytosis (cytosine means excess (along with aphelia)). This is increased red cell production.
How long does the process of up regulation of reticulocyte formation take in response to anaemia?
A few days.
What do automated analysers measure and calculate?
They measure
- Hb conc
- Number of red cells
- Size of red cells
They calculate
- Haematocrit
- Mean cell haemoglobin (from number of red cells and Hb conc)
- Mean cell haemoglobin conc (this ensures all parameters are working correctly).
What parameters does a full blood count look for?
HGB- haemoglobin RBC- red blood cell HCT- haematocrit MCV- mean cell volume (how big the cells are) MCH- mean cell haemoglobin MCC- mean cell haemoglobin concentration RET- reticulocyte count And also white cells like neutrophils, lymphocytes, basophils, eosinophils.
What does a reticulocyte count allow you to assess?
The marrow response to the problem at hand.
What will a blood film allow you to look at?
The cellular morphology
How is anaemia classified?
By morphological characteristics or pathophysiology
How is pathophysiological classification of anaemia split?
Into decreased production (low reticulocyte count) or increased destruction (high reticulocyte count).