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Haematology Week 1 > Haemolysis > Flashcards

Haemolysis Flashcards

1
Q

What is haemolysis?

A

Premature red cell destruction

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2
Q

What products of red cell breakdown are a) recycled? b) broken down?

A

a) iron and globin chains b) haem group (protoporphyrin)

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3
Q

The haem group is first broken down into what? And then into what? For this reason, the first sign of somebody who is haemolysing may be what?

A

Biliverdin / bilirubin / they become jaundiced

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4
Q

What are the two main consequences of haemolysis?

A

Erythroid hyperplasia (more red cell production in the bone marrow) and presence of excess red cell breakdown products

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5
Q

What is compensated haemolysis?

A

When there is increased red cell destruction which is compensated for by increased red cell production

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6
Q

What happens to Hb in compensated haemolysis? Do patients become anaemic?

A

It is normal / no

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7
Q

What is decompensated haemolysis?

A

Increased rate of red cell destruction exceeds the bone marrow capacity for red cell production

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8
Q

What happens to Hb in decompensated haemolysis? Do patients become anaemia?

A

It is low / yes

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9
Q

It is difficult to measure red cell survival directly. Therefore, we rely on detecting the consequences of haemolysis to determine the cause. What are these?

A

Increased red cell production and detection of breakdown products

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10
Q

What are the bone marrow’s two main responses to haemolysis?

A

Erythroid hyperplasia and reticulocytosis

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11
Q

Due to the presence of reticulocytes, when someone is haemolysing what will be seen on a blood film?

A

Large, polychromatic red cells (reticulocytes)

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12
Q

Is the presence of reticulocytes diagnostic of haemolysis?

A

No, because it can also be seen as a response to bleeding or iron therapy

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13
Q

How is erythroid hyperplasia actually visualised? Is this done often?

A

Bone marrow biopsy - no, only when you think the person is haemolysing because of a disorder that would show up on a biopsy

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14
Q

Where are red cells broken down in extravascular haemolysis?

A

They are taken up by the reticuloendothelial system, predominantly the liver and spleen

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15
Q

Where are red cells broken down in intravascular haemolysis?

A

Within the circulation

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16
Q

What effect does extravascular haemolysis have on the site of red cell destruction? Give examples?

A

It causes hyperplasia at the site of destruction - usually splenomegaly +/- hepatomegaly

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17
Q

In extravascular haemolysis, the protoporphyrin that forms the haem group gets broken down, leading to the release of what?

A

Unconjugated bilirubin in the blood / urobilinogen in the urine

18
Q

In extravascular haemolysis, the release of unconjugated bilirubin into the blood leads to what clinical symptoms/signs?

A

Jaundice and gallstones

19
Q

Describe the abnormality with the breakdown products in extravascular haemolysis?

A

They are normal breakdown products, just seen in excess

20
Q

In intravascular red cell destruction, there is release of what into the circulation?

A

Free Hb (haemoglobinaemia) and Hb bound to albumin (methaemalbuminaemia)

21
Q

In intravascular red cell destruction, there is release of what into the urine?

A

Hb (haemoglobinuria) and haemosiderin (haemosiderinuria)

22
Q

How does the presence of Hb in the urine look?

A

Looks pink initially, but turns black when left to stand

23
Q

What are some causes of intravascular red cell destruction?

A

ABO incompatibility, G6PD deficiency, severe falciparum malaria (Blackwater fever)

24
Q

Describe the abnormality with the breakdown products which is seen in intravascular haemolysis?

A

Abnomal breakdown products are produced - these can be life threatening

25
Q

Haemolysis can be classified by the site of red cell defect. Give some examples?

A

Abnormal cell membrane, Hb or red cell metabolism

26
Q

What are the two main categories of acquired premature normal red cell destruction?

A

Immune or mechanical

27
Q

What are the two main categories of immune premature red cell destruction?

A

Autoimmune or alloimmune haemolysis

28
Q

Autoimmune haemolysis can be caused by what two antibodies?

A

Warm (IgG) or cold (IgM)

29
Q

How is autoimmune haemolysis diagnosed?

A

Direct Coombe’s test - will show agglutination if positive for antibody

30
Q

What is an example of alloimmune haemolysis which is caused by an immune response resulting in the production of antibodies?

A

Haemolytic transfusion reaction

31
Q

What is an example of alloimmune haemolysis which is caused by passive transfer of antibodies?

A

Haemolytic disease of the newborn

32
Q

What are some examples of mechanical causes of acquired premature destruction of red blood cells?

A

DIC, HUS, thrombotic thrombocytopenic purpura, leaking heart valve, infections e.g. malaria

33
Q

Mechanical valve related microangiopathic haemolytic anaemia (MAHA) will show what on a blood film?

A

Red cell fragmentation

34
Q

What is seen on a blood film of a patient with severe burns?

A

Microspherocytes and sheared red cells

35
Q

What are some examples of acquired red cell membrane defects which can lead to haemolysis?

A

Liver disease (Zieve’s syndrome), vitamin E deficiency, paroxysmal noctural haemoglobinuria

36
Q

Zieve’s syndrome is an example of an acquired red cell membrane defect. It involves a triad of what?

A

Haemolysis, alcoholic liver disease and hyperlipidaemia

37
Q

Give two examples of causes of haemolysis due to congenital abnormalities of the red cell membrane?

A

Hereditary spherocytosis and G6PD deficiency

38
Q

What is an example of haemolysis caused by congenital abnormal haemoglobin?

A

Sickle cell disease

39
Q

What is a test you could do that is highly sensitive for haemolysis - i.e. if this is not raised then they are unlikely to be haemolysing?

A

Serum haptoglobins

40
Q

What seen on a blood film is suggestive of mechanical damage to the red cell membrane?

A

Spherocytes

41
Q

Red cell fragments on a blood film are suggestive of what?

A

Mechanical damage from an artifical heart valve

42
Q

What is seen on a blood film which is suggestive of oxidative damage?

A

Heinz bodies

Haematology Week 1 (11 decks)

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