HAEMATOLOGY Flashcards
Define Anaemia
Anaemia is a decrease in haemoglobin below reference range due to a reduction in cell mass or increased plasma volume
What can anaemia be subdivided into? What are the names of the categories?
Anaemia can be classified based on the Mean Corpuscular Volume (MCV).
It is based on the size of the red blood cell (the MCV)
- Microcytic anaemia(low MCV indicating small RBCs)
- Normocytic anaemia(normal MCV indicating normal sized RBCs)
- Macrocytic anaemia(large MCV indicating large RBCs)
Nearly all types of anaemia present with the same symptoms and signs - What are the general symptoms for anaemia?
Symptoms:
* Fatigue
* Lethargy
* Dyspnoea – difficulty or laboured breathing
* Palpitations
* Headache
Nearly all types of anaemia present with the same symptoms and signs - What are the general signs for anaemia?
Signs
* Pale skin
* Pale mucous membranes – nose and eyelids
* Systolic flow murmur
* Tachycardia (compensatory to meet demand)
What does MCV stand for?
MCV stands for Mean Corpuscular Volume, which is a measure of the average size of red blood cells.
What does MCHC stand for?
MCHC stands for Mean Corpuscular Hemoglobin Concentration, which is a measure of the average amount of hemoglobin in a red blood cell.
What are the general consequences of anaemia?
Consequences of anaemia:
* Reduced O2 transport
* Tissue hypoxia
Compensatory changes:
○ Increased tissue perfusion
○ Increased O2 transfer to tissues
○ Increased RBC production
What are the main causes of Microcytic anaemia?
TAILS
Thalassaemias
Anaemia of chronic disease
Iron deficiency
Lead poinsoing
Sideroblastic anaemia
Normal physiology - what are the two types of Iron you get in your diet?
How are they absorbed from the duodenum?
Heme Iron - found in the Fe2+ state - can be directly absorbed into the duodenal cells, where it is broken down to release Fe2+ molecules.
non-heme iron found in the Fe3+, state. - needs to be converted into heme iron first, by enzymes activated by the stomach acid before it can be absorbed into the duodenum.
Normal Physiology - what does iron do in the structure of haemoglobin?
Haemoglobin is made of four haem molecules which contain iron.
The iron in haem is what binds to Oxygen, Tso each haemoglobin molecule can bind four molecules of oxygen.
In addition, iron is also an important part of proteins like myoglobin, which delivers and stores oxygen in muscles; and mitochondrial enzymes like cytochrome oxidase, which help generate ATP
Normal Physiology - what to Fe2+ molecules bind to in
a) Cells
b) for transport in the blood?
a) Fe2+ molecules then bind to a protein in the duodenal cells called ferritin, which temporarily stores the iron. Fe2+ binding to ferritin is how iron is stored in body cells
b) When needed to be transported in the blood, Fe2+ molecules are converted into Fe3+ molecules and carried by Transferrin
Anaemia caused by iron deficiency is the most common cause of anaemia worldwide. - What are some causes of it?
- Vegetarian/ vegan diet -
- H.pylori infection causes gastric ulcers and bleeding, and takes iron for itself
- Pregnancy
- Young children and adolescents
- Inflammatory bowel disease/Coeliac impairs iron absorption
- Certain drugs e.g. PPIs inhibit gastric acid, so non haem cannot be absorbed as it is not converted into haem iron
Heavy menstruation
What happens to RBC production as a result of iron deficiency?
Leads to impaired haemoglobin production.
Since there’s not enough haemoglobin for a normal sized RBC, the bone marrow starts pumping out microcytic RBCs. - these have less Haemoglobin so are called hypochromic, as appear pale
Microcytic RBCs can’t carry enough oxygen to the tissues - hypoxia.
Hypoxia signals the bone marrow to increase RBC production.
The bone marrow goes into overdrive and pumps out incompletely formed RBCs.
What are some signs of iron deficiency anaemia?
○ Pallor
○ Conjunctival pallor
○ Glossitis inflammation of the tongue
○ Koilonychia (spoon-shaped nails)
○ Angular stomatitis sored on the corners of the mouth
What are some symptoms of iron deficiency anaemia?
- Symptoms
○ Fatigue
○ Dyspnoea
○ Dizziness
○ Headache
○ Nausea
○ Bowel disturbance
○ Hairloss
○ Pica (abnormal cravings)
○ Possible exacerbation of cardiovascular co-morbidities causing angina, palpitations, and intermittent claudication.
What investigations would you do in suspected iron deficiency anaemia?
FBC blood count - look for low Hb, Low MCV, Low MCHC
Iron Studies - looking at:
- serum iron,
- serum ferritin,
- total iron binding capacity,
- transferrin saturation
What would someone with iron deficiency anaemia’s iron studies (serum iron, serum ferritin, total iron binding capacity, and transferrin saturation) look like?
○ Serum iron - low
○ Serum ferritin: low in anaemia
○ Total iron binding capacity: can be used as a marker for how much transferrin is in the blood. Increased in anaemia
○ Transferrin saturation: gives a good indication of the total iron in the body. Decreased in anaemia
Note - ferritin is an acute phase protein, so can also increase with inflammation (i.e. due to infection/malignancy)
What are the management options of iron deficiency anaemia?
- Treat the underlying cause
- Oral iron supplements: ferrous sulphate or ferrous fumarate
○ Side effects: constipation and black coloured stools, diarrhoea, nausea and dyspepsia/epigastric discomfort. - Iron infusion e.g. cosmofer
- Blood transfusions may be needed in severe cases
What are some chronic disease that can lead to anaemia?
What type of anaemia?
Microcytic anaemia
Causes:
Crohn’s
Rheumatoid arthritis
TB
Systemic lupus erythematosus
Malignant disease
CKD
What is
a) Alpha Thalassaemia?
b) Beta Thalassaemia?
What is it’s genetic pattern, autosomal or sex linked, dominant or recessive?
Alpha Thalassaemia - genetic disorder where there’s a deficiency in production of the alpha globin chains of haemoglobin
Beta thalassaemia - is a genetic disorder where there’s a deficiency in the production of the β-globin chains of haemoglobin.
BOTH AUTOSOMAL RECESSIVE
Where is thalassaemia most present, and why?
Where is
a) Alpha Thalassaemia most present
b) Beta Thalassaemia most present
- Thalassaemia is prevalent in areas with malaria as there is evidence to suggest that thalassaemic red cells provide immunity against the parasite.
- Alpha thalassaemia: Asian and African descent
- Beta thalassaemia: South-East Asian, Mediterranean, and Middle Eastern descent
Alpha thalassaemia - How many alleles, are responsible for alpha chain synthesis?
What does someone with one gene deletion experience?
What would someone with 2 gene deletions experience?
4 alleles, on chromosome 16
One gene deletion does not cause symptoms of alpha thalassaemia.
2 gene deletion - mildly anaemic with near-normal haemoglobin electrophoresis.
Alpha thalassaemia -
What would someone with 3 gene deletions experience, what do the beta chains form?
3 gene deletions are unable to form alpha chains. The beta chains form tetramers (HbH), which damage erythrocytes causing moderate to severe disease
Alpha thalassaemia -
What would someone with 4 gene deletions experience, what do the beta chains form?
4 gene deletions die in utero because the gamma chains form tetramers (Hb Barts), which cannot carry oxygen efficiently