Anaemia and Polycythaemia Flashcards Preview

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Flashcards in Anaemia and Polycythaemia Deck (42)
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What is anaemia?

A reduction in the amount of haemoglobin in a given volume of blood below what would be expected in comparison with a healthy subject of the same age and gender


Other than a reduction in the absolute amount of haemoglobin in the blood stream, what else could cause anaemia?

An increase in the plasma volume can decrease the haemoglobin concentration


Why would this type of anaemia only be transient in a healthy individual?

The excess fluid would be excreted in a healthy individual


Broadly speaking, state four mechanisms of anaemia.

Reduced production of red blood cells/haemoglobin in the bone marrow
Loss of blood from the body (haemorrhage)
Reduced survival of red blood cells (haemolytic)
Pooling of red blood cells in a very large spleen


For each type of anaemia, state whether they are usually hypochromic, normochromic or hyperchromic.

Microcytic – hypochromic
Normocytic – normochromic
Macrocytic - normochromic


State the common causes of microcytic anaemia.

Problem with Haem synthesis
 Iron deficiency
 Anaemic of chronic disease
Problem with globin synthesis
 Alpha thalassemia
 Beta thalassemia


What mechanism usually causes macrocytic anaemia?

It usually results from abnormal haemopoiesis
The cells fail to divide properly


What is megaloblastic erythropoiesis? Describe the appearance of a megaloblast.

Megaloblastic erythropoiesis refers to a delay in the maturation of the nucleus while the cytoplasm continued to mature and the cell continues to grow
A megaloblast is an abnormal bone marrow erythroblast
They are large and show nucleo-cytoplasmic dissociation


What is an alternative mechanism of macrocytosis?

You can get premature release of cells from the bone marrow
Reticulocytes are about 20% larger than mature red cells so reticulocytosis would increase the MCV


State the two most common causes of megaloblastic anaemia.

B12 deficiency
Folate deficiency


State some other common causes of macrocytic anaemia.

Drugs that interfere with DNA synthesis (e.g. chemotherapy)
Liver disease
Ethanol toxicity
Recent major blood loss with adequate iron stores (if you’ve lost blood, the bone marrow will start spitting out reticulocytes to compensate)
Haemolytic anaemia (reticulocytosis due to the loss of red cells)


State three mechanisms of normocytic normochromic anaemia.

Recent blood loss
Failure to produce red blood cells
Pooling of red blood cells in the spleen


State five causes of normocytic normochromic anaemia.

Peptic ulcer
Oesophageal varices
Failure of production of red blood cells
 Early stages of iron deficiency and ACD
 Renal failure
 Bone marrow failure
 Bone marrow infiltration


Define haemolytic anaemia.

Anaemia resulting from shortened survival of red blood cells in the circulation


State two different classifications of haemolytic anaemia.

Haemolysis can be inherited (resulting from abnormalities of the cell membrane, haemoglobin or the enzymes in the red blood cell)
It can be acquired usually resulting from extrinsic factors such as micro-organisms, chemicals or drugs
Haemolytic anaemia can also be described as intravascular if there is very acute damage to the red cell
It can also be classified as extravascular when the spleen removes defective red cells


State some inherited abnormalities that can cause haemolytic anaemia.

Abnormal red cell membrane
Abnormal haemoglobin
Defect in the glycolytic pathway
Defect in the enzymes of the pentose shuttle


State some acquired abnormalities that cause haemolytic anaemia.

Damage to the red cell membrane
Damage to the whole red cell
Oxidant exposure


Explain how G6PD Deficiency can cause haemolytic anaemia.

G6PD is part of the pentose phosphate pathway
This is the only source of reduced glutathione in red blood cells
Because of the oxygen-carrying role of red blood cells, they are at constant risk of oxidant damage
So people with G6PD deficiency are at risk of haemolytic anaemia in states of oxidative stress


When would you suspect haemolytic anaemia?

Otherwise unexplained anaemia that is normochromic and usually either normocytic or macrocytic
Evidence of morphologically abnormal red cells
Evidence of increased red blood cell turnover
Evidence of increased bone marrow activity


What does the presence of fragments in the blood film suggest?

This suggests that red blood cells are being broken down within the circulation (in the small circulation)


What condition causes breakdown of red blood cells in small blood vessels?

Microangiopathic haemolytic anaemia


State some important signs of haemolytic anaemia.

Jaundice – because of the increased break down of red blood cells there is an increase in bilirubin
The increase in bilirubin can also increase the risk of getting gallstones


State examples of inherited diseases causing haemolytic anaemia that have defects at the following sites:
a. Membrane
b. Haemoglobin
c. Glycolytic Pathway
d. Pentose Shunt

a. Membrane
Hereditary spherocytosis
b. Haemoglobin
Sickle cell anaemia
c. Glycolytic Pathway
Pyruvate kinase deficiency
d. Pentose Shunt
G6PD deficiency


State examples of acquires disease causing haemolytic anaemia that have defects at the following sites:
a. Membrane - immune
b. Whole red cell - mechanical
c. Whole red cell - oxidant
d. Whole red cell - microbiological

a. Membrane – immune
Autoimmune haemolytic anaemia
b. Whole red cell –mechanical
Microangiopathic haemolytic anaemia
c. Whole red cell – oxidant
Drugs and chemicals
d. Whole red cell – microbiological


What is hereditary spherocytosis?

This is haemolytic anaemia or chronic compensated haemolysis resulting from an intrinsic inherited defect of the red cell membrane
After entering the circulation, the cells lose membrane in the cell and become spherocytic


What are the features of red cells in hereditary spherocytosis?

They are LARGE and ROUND and have an increased MCHC


How does the bone marrow respond to the increased extravascular haemolysis in hereditary spherocytosis?

It increases the output of red cells leading to polychromasia and reticulocytosis


What is an effective treatment for hereditary spherocytosis?



Why is a good diet important in patients with hereditary spherocytosis?

They have increased bone marrow activity and erythropoiesis so they need a supply of B12, folate and iron to keep producing red blood cells


Describe the pattern of inheritance of G6PD deficiency.

X linked recessive