Haemolysis

Question 1

Define haemolysis:

Answer 1

Premature red blood cell destruction

Question 2

List some reasons why RBCs are vulnerable to being damaged:

Answer 2

Their biconcave shape
No mitochondria = limited metabolic reserve
No nucleus

Question 3

What is compensated haemolysis:

Answer 3

When the increased red blood cell destruction is beign compensated by increased RBC production
Therefore Hb levels normal

Question 4

What is decompensated haemolysis?

Answer 4

Haemolytic anaemia
When the rate of RBC destruction exceeds the capacity of the bone marrow to produce RBCs
Low HB

Question 5

State two consequences of haemolysis:

Answer 5

Erythroid hyperplasia

Excess RBC breakdown products e.g. bilirubin

Question 6

What is the bone marrow’s response to haemolysis?

Answer 6

Reticulocytosis

Erythroid hyperplasia

Question 7

Reticulocytes have a nucleus : true/false?

Answer 7

FALSE

They do not have a nucleus

Question 8

How is haemolysis classified?

Answer 8

Extravascular i.e. RBCs being taken up by reticuloendothelial system (spleen / liver)
Intravascular i.e. red ells destroyed within the circulation

Question 9

Which type of haemolysis is more common?

Answer 9

Extravascular

Question 10

What might be seen on examination pf a patient with extravascular haemolysis?

Answer 10

Hyperplasia of site of destruction i.e. hepatomegaly or splenomegaly

Question 11

What symptoms might be seen in extravascular haemolysis and why?

Answer 11

Jaundice & gallstones –> unconjugated bilirubin

Discoloured urine –> Urobilinogenuria

Question 12

What is specific about the products seen in extravascular destruction?

Answer 12

They are normal blood components in excess

Question 13

What is specific about the products seen in intravascular destruction?

Answer 13

Abnormal products seen in the blood.

Question 14

List some products seen in the blood in intravascular red blood cell destruction?

Answer 14

Haemoglobinaemia (Free Hb in circulation)Methaemalbuminaemia
Haemoglobinuria (pink urine which turns black on standing)
Haemosiderinuria

Question 15

List some causes of intravascular haemolysis:

Answer 15

ABO incompatible blood transfusion
G6PD deficiency
Severe falciparum malaria
Rare (PNH / PCH)

Question 16

What investigations are done for haemolysis:

Answer 16

FBC and film 
Reticulocyte count
Serum unconjugated bilirubin
Serum haptoglobins
Urinary urobilinogen

Question 17

What might be seen on a blood film of a patient with haemolysis?

Answer 17

Spherocytes
Red cell fragments
Heinz bodies
Sickle cells

Question 18

What is a specific investigation for haemolysis?

Answer 18

Direct Coombs test

Question 19

What antibodies are associated with autoimmune haemolysis?

Answer 19

Warm - IgG

Cold - IgM

Question 20

List some causes of warm IgG

Answer 20

Idiopathic
Autoimmune e.g. SLE
Lymphoproliferative 
Drugs e.g. penicillin
Infections

Question 21

List some causes of Cold IgM

Answer 21

Idiopathic
Infections e.g. EBV, mycoplasma
Lymphoproliferative disorders

Question 22

Outline the mechanism of the direct coombs test:

Answer 22

Patients RBCs are mixed with mouse antibodies coated with human anti-IgG and complement
If patient is positive, blood will agglutinate

Question 23

Give some examples of alloimmune haemolysis:

Answer 23

Immune response e.g. haemolytic transfusion reaction (immediate IgM = intravascular and delayed IgG = extravascular)

Passive transfer of antibody e.g. haemolytic disease of the newborn

Question 24

List some causes of mechanical red cell destruction:

Answer 24

Disseminated intravascular coagulation
Haemolytic uraemic syndrome 
TTP
Leaking heart valve
Infections e.g. malaria

Question 25

What bacteria causes HUS?

Answer 25

E. Coli 0157

Question 26

What type of anaemia is associated with a mechanical heart valve and what is seen on the blood film?

Answer 26

Microangiopathic haemolytic anaemia (MAHA) Red cell fragmentation due to mechanical damage

Question 27

When are microspherocytes seen in haemolytic anaemias?

Answer 27

When caused by severe burn injuries | RBCs are sheared when passing through damaged capillaries

Question 28

List some causes of membrane defects that lead to haemolysis:

Answer 28

``` Liver disease (Zieve's syndrome) Vit E deficiency Paroxysmal Nocturnal Haemoglobinuria ```

Question 29

What is Zieve's syndrome?

Answer 29

An acute metabolic disorder which results from withdrawal after prolonged exposure to alcohol. Defined by haemolytic anaemia, hyperlipidaemia and jaundice

Question 30

What genetic condition can cause abnormal RBC membranes, leading to haemolysis?

Answer 30

Hereditary Spherocytosis

Question 31

What does a G6PD deficiency cause?

Answer 31

Leads to failure to cope with oxidative stress and a failure to produce ATP, causing the metabolism process to fail

Question 32

How is spherocytosis inherited?

Answer 32

Dominant