Red Cells 2: acquired anaemias Flashcards
Definition of Anaemia
Low haemoglobin
However this has to be below the normal range for their age / sex
What happens to your Hb as you get older?
There is a drop in your Hb
Reference ranges for Hb in M and F
- Male 12-70 (140-180)
- Male >70 (116-156)
- Female 12-70 (120-160)
- Female >70 (108-143)
Lower levels of Hb in menstruating females due to drop in iron
General symptoms/features of anaemia (caused by reduced O2 delivery to tissues)
- Tiredness/pallor
- Breathlessness
- Swelling of ankles
- Dizziness – on standing up too quickly etc
- Chest pain – myocardial ischaemia
These depend on age, speed of onset and Hb level
Common underlying causes of anaemia
- If evidence of bleeding
- Menorrhagia
- GI bleeding - Dyspepsia
- PR bleeding
- Symptoms of malabsorption - GI symptoms - unable to absorb things necessary to make blood i.e B12
- Diarrhoea
- Weight loss
- Jaundice - haemolysing
- Splenomegaly/lymphadenopathy - haemotolgical condition
Anaemia pathophysiology
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Understanding blood count results
When you get a blood count you get Hb level and a whole lot of indices telling you all about the size, number and shape of the RBCs. The most important ones are:
- MCH = mean cell haemoglobin (amount of Hb in the cells)
- MCV = mean cell volume (cell size)
From this you can give a morphological description of anaemia – and a clue as to cause! Machines cannot tell you shape of blood but it can tell you whether there is an abnormal average size and amount of Hb in cells even if they are misshapen under microscope
How do we describe anaemias? (3)
- Hypochromic microcytic anaemia – small, pale cells
- Normochromic normocytic – normal size, normal colour
- Macrocytic anaemia – big cells and are usually pale (not hyperchromic – as this would mean they have lots of Hb)
Once you have looked at the blood results and find out it is hypochromic microcytic anaemia. What test will you do next to confrim this?
Serum ferritin test
Iron deficiency is the commonest cause of hypochromic microcytic and ferritin is a measure of the body’s iron stores.
- If your serum ferritin is low = iron deficiency
- If your serum ferritin is normal or increased then there can be other things going on. It can go up if you have inflammation or liver damage.
- Thalassaemia has normal ferritin but small cells. They can develop iron deficiency too from GI bleed etc.
- Secondary anaemia
Once you have looked at the blood results and find out it is normochromic normocytic anaemia. There are lots of causes of this so what test will you do next to investigate it further / confrim this?
A reticulocyte count
This can tell you if your bone marrow is working or not.
Why might you have a normal or low reticulocyte count?
Low:
- Secondary anaemia / anaemia of chronic disease - renal impairment - kidneys don’t make erythropoietin (EPO) which tells bone marrow to make RBCs
- Marrow infiltration - aplastic anaemia - cells appear normal but just aren’t enough of them - can be caused by malignancy etc
Why might you have a raised reticulocyte count in Normochromic normocytic anaemia?
High:
- In acute blood loss - it takes a long period of bleeding to empy body’s iron stores so in acute blood loss you just become anaemic but you wouldn’t be iron deficient by then because your body would still have iron stores. In acute blood loss you get normochromic anaemia and body responds by making reticulocytes to compensate for loss of RBCs
- Haemolysis - increased breakdown of cells => reduced Hb => compensation by bone marrow => increased retic count
What is Secondary anaemia / anaemia of chronic disease?
Inability to use iron efficiently - increased hepcidin in inflammation blocks ferroportin and so Fe is stuck in places where it shouldn’t be and not being used efficiently for erythropoeisis. Your ferritin stores may be normal or even raised if underlying inflammatory process as Fe is an acute phase reactant.
- 70% normochromic normocytic
- Very chronic secondary anaemias where there is a lot of inflammation causes abnormal Fe utilisation (remember it plas important role in protecting body from microorganisms) that cells become microcytic = 30% hypochromic microcytic
Once you have looked at the blood results and find out it is macrocytic anaemia. What tests will you do next to investigate it further / confrim this?
- B12/folate
- Bone marrow
The commonest cause of a macrocytic anaemia is B12 or folate deficiency. If your B12/folate results are normal then you are looking at a problem with the bone marrow such as malignancies
Look
There is no pathway for excretion of excess iron = you need iron chelation therapy/drugs