Haemolysis

Question 1

What is haemolysis?

Answer 1

Premature red cell destruction

Question 2

Why are red cells commonly damaged?

Answer 2

Limited metabolic reserve due to lack of mitochondria

Unable to generate new proteins in circulation due to no nucleus

Question 3

What occurs in compensated haemolysis?

Answer 3

There is increased red cell destruction compensated for by increased red cell production

Question 4

What occurs in haemolytic anaemia?

Answer 4

The increased rate of red cell destruction exceeds bone marrow capacity for red cell production

Question 5

What are the two main consequences of haemolysis?

Answer 5

Increased bone marrow red cell production

Excess red cell breakdown (hyperbilirubinaemia)

Question 6

What is the response of the bone marrow to haemolysis?

Answer 6

Reticulocytosis

Erythroid hyperplasia

Question 7

What occurs in extravascular haemolysis?

Answer 7

The red cells are taken up by the reticuloendothelial system (spleen and liver)

Question 8

What occurs in intravascular haemolysis?

Answer 8

The red cells are destroyed within the circulation

Question 9

Which is more common - extra or intravascular haemolysis?

Answer 9

Extra

Question 10

Extravascular red cell destruction causes hyper/hypoplasia at site of destruction

Answer 10

Hyperplasia

Question 11

Give two clinical findings that are seen in extravascular red cell destruction

Answer 11

Unconjugated bilirubinaemia

Urobilinogenuria

Question 12

What are the four main clinical findings seen in intravascular haemolysis?

Answer 12

Haemoglobinaemia
Methaemalbuminaemia
Haemoglobinuria
Haemosiderinuria

Question 13

Which tends to be more life threatening - extravascular haemolysis or intravascular haemolysis?

Answer 13

Intravascular

Question 14

Give some causes of intravascular haemolysis

Answer 14

ABO incompatible blood transfusion
G6PD deficiency
Falciparum malaria

Question 15

What investigations are used to confirm a patient’s haemolytic state?

Answer 15

FBC
Reticulocyte count
Unconjugated bilirubin
Haptoglobins
Urobilinogen

Question 16

What investigation is used to identify the cause of haemolysis?

Answer 16

Blood film

Question 17

What antibodies will cause autoimmune haemolysis?

Answer 17

IgG (warm)

IgM (cold)

Question 18

Give some causes of IgG autoimmune haemolysis

Answer 18

Idiopathic
SLE
Lymphoproliferative disorders
High dose penicillin

Question 19

Give some causes of IgM autoimmune haemolysis

Answer 19

Idiopathic
EBV
Lymphoproliferative disorders

Question 20

What occurs in a direct Coombs’ test?

Answer 20

The patients RBCs are incubated with anti-human IgG to see if agglutination occurs

Question 21

A positive or negative direct Coombs’ test is indicative of autoimmune haemolysis?

Answer 21

Positive

Question 22

What occurs in alloimmune haemolysis?

Answer 22

The immune system produces antibodies against foreign antigens

Question 23

Give two examples of alloimmune haemolysis

Answer 23

Haemolytic transfusion reaction

Haemolytic disease of the newborn

Question 24

Give some causes of mechanical red cell destruction

Answer 24

Disseminated intravascular coagulation
Haemolytic uraemic syndrome
Leaking heart valve
Severe burns

Question 25

Give some acquired causes of membrane defects causing haemolysis

Answer 25

``` Liver disease (Zieve's syndrome) Vitamin E deficiency Paroxysmal nocturnal haemoglobinuria ```

Question 26

What features are seen in Zieve's syndrome?

Answer 26

Haemolysis Alcoholic liver disease Hyperlipidaemia

Question 27

What is the main genetic cause of red cell membrane abnormalities?

Answer 27

Hereditary spherocytosis

Question 28

What substances can be faulty causing abnormal red cell metabolism?

Answer 28

G6PD | ATP

Question 29

Which drug causes oxidative damage to red cells?

Answer 29

Dapsone

Question 30

What is the main genetic cause of abnormal haemoglobin?

Answer 30

Sickle cell disease