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MCDone > Anaemia and Polycythaemia > Flashcards

Anaemia and Polycythaemia Flashcards

1
Q

What is anaemia?

A

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

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2
Q

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

A

An increase in the plasma volume can decrease the haemoglobin concentration

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3
Q

Why would anaemia where excess plasma only be transient in a healthy individual?

A

The excess fluid would be excreted in a healthy individual

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4
Q

Broadly speaking, state four mechanisms of anaemia.

A

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

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5
Q

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

A

Microcytic – hypochromic
Normocytic – normochromic
Macrocytic - normochromic

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6
Q

State the common causes of microcytic anaemia.

A

Problem with Haem synthesis

Problem with globin synthesis

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7
Q

What mechanism usually causes macrocytic anaemia?

A

It usually results from abnormal haemopoiesis

The cells fail to divide properly

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8
Q

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

A

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

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9
Q

What is an alternative mechanism of macrocytosis?

A

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

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10
Q

State the two most common causes of megaloblastic anaemia.

A

B12 deficiency

Folate deficiency

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11
Q

State some common causes of macrocytic anaemia.

A

Megaloblastic anaemia
Haemolytic anaemia
Blood loss with adequate iron stores
Ethanol toxicity

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12
Q

State three mechanisms of normocytic normochromic anaemia.

A

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

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13
Q

Define haemolytic anaemia.

A

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

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14
Q

State some inherited abnormalities that can cause haemolytic anaemia.

A

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

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15
Q

State some acquired abnormalities that cause haemolytic anaemia.

A

Damage to the red cell membrane

Damage to the whole red cell

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16
Q

Explain how G6PD Deficiency can cause haemolytic anaemia.

A

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

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17
Q

When would you suspect haemolytic anaemia?

A

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

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18
Q

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

A

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

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19
Q

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

A

Microangiopathic haemolytic anaemia

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20
Q

State some important signs of haemolytic anaemia.

A

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

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21
Q

What are the features of red cells in hereditary spherocytosis?

A

They are LARGE and ROUND and have an increased MCHC

22
Q

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

A

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

23
Q

What is an effective treatment for hereditary spherocytosis?

A

Splenectomy

24
Q

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

A

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

25
Q

What can G6PD deficiency cause?

A

Intermittent, severe intravascular haemolysis as a result of infection or exposure to an exogenous oxidant

26
Q

What causes acute haemolytic anaemia?

A

Results from the production of antibodies against red cell antigens
This is very sudden and dramatic. An AUTOIMMUNE disease

27
Q

Describe how acute haemolytic anaemia can lead to spherocytosis.

A

The immunoglobulin bound to the red cell is recognised by splenic macrophages, which remove parts of the cell membrane leading to spherocytosis

28
Q

State two causes of spherocytosis.

A

Hereditary spherocytosis

Autoimmune haemolytic anaemia

29
Q

Describe the diagnosis of acute haemolytic anaemia.

A

Finding spherocytes
Detecting immunoglobulin on the red cell surface Detecting antibodies to red cell antigens or other antibodies in the plasma

30
Q

Which red blood cell parameters are increased in polycythaemia?

A

RBC
Hct
Hb

31
Q

What is the term given to a condition where these parameters are increased but the absolute amount of haemoglobin is not increased?

A

Pseudopolycythaemia (or apparent polycythaemia)

This is due to a decrease in plasma volume

32
Q

What are the consequences of polycythaemia?

A

Hyperviscosity of the blood

This can lead to vascular obstruction

33
Q

Cause of defect in haem group

A

Fe deficiency

Anaemia of chronic disease

34
Q

Cause of defect in globin group

A

A and b thalassaemia

35
Q

Common causes of blood loss in normocytic anaemia

A

Peptic ulcer
Esophageal varices
Trauma

36
Q

Causes of failing to produce RBCs in normocytic anaemia

A

Bone marrow failure
Renal failure (EPO)
Anaemia of chronic disease early stages

37
Q

Cause of pooling of red blood cells in spleen

A

Hypersplenism

38
Q

3 ways to classify haemolytic anaemia

A

Intrinsic/external factors
Hereditary/acquired
Intra/extravascular

39
Q

Ways acquired haemolytic anaemia can damage RBC

A

Cell membrane

Whole cell

40
Q

Causes of damage to RBC membrane in haemolytic anaemia

A

Autoimmune haemolytic anaemia

Snake venom

41
Q

Causes of damage to whole cell in haemolytic anaemia

A

Oxidant damage
Malaria infection
Microangiopathic haemolytic anaemia

42
Q

Ways inherited haemolytic anaemia can damage RBCs

A

Cell membrane defect
Hb defect
Glycolytic pathway defect
Pentose shunt enzymes defect

43
Q

Cause of cell membrane damage in inherited haemolytic anaemia

A

Hereditary spherocytosis

44
Q

Cause of Hb defect in inherited haemolytic anaemia

A

SCD

45
Q

Cause of glycolytic pathway defect in inherited haemolytic anaemia

A

Pyruvate kinase deficiency

46
Q

Cause of pentonse shunt pathway defect in inherited haemolytic anaemia

A

G6P deficiency

47
Q

3 causes of polycythaemia

A

Too much blood
Increased erythropoietin
Polycythaemia vera

48
Q

Cause of too much blood polycythaemia

A

Doping

Medical negligence

49
Q

Cause of too much erythropoeitin polycythaemia

A

Hypoxia-
Doping
Renal tumour

50
Q

What is polycythaemia vera

A

Myeloproliferative neoplasm producing too many RBCs independent of EPO

51
Q

Treatment for polycythaemia

A

Remove blood

Drugs to reduce bone marrow activity

52
Q 
Cause of polycythaemia in these instances
Healthy athlete
Breathless and cyanosis
Abdominal mass
Splenomegaly
A

Doping
Hypoxia
Renal tumour
Polycythaemia vera

MCDone (43 decks)

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