Haemolysis

Question 1

What is the definition if haemolysis?

Answer 1

Pemature red cell destruction

i.e. shortened red cell survival

Question 2

What 3 reasons mean red cells are susceptible to damage?

Answer 2

1. They need biconcave shape
2. Limited metabolic reserve (no mitochondria)
3. Can’t generate new proteins once in circulation (no nucleus)

Question 3

What is compensated haemolysis?

Answer 3

Increased red cell destruction compensated by increased red cell production

Question 4

What is haemolytic anaemia (decompensated haemolysis)?

Answer 4

Increased rate of red cell destruction exceeding bone marrow capacity for red cell production

Question 5

What are consequences of haemolysis?

Answer 5

Erythroid hyperplasia

Excess red cell breakdown products e.g. biliruben

Question 6

What is Erythroid hyperplasia?

Answer 6

Increased bone marrow red cell production

Question 7

What is the bone marrow response to haemolysis?

Answer 7

Reticulocytosis

Erythroid hyperplasia

Question 8

Are reticulocytes nucleated ells?

Answer 8

No

Question 9

What is ribosomal RNA labelled with to count flourescent cells?

Answer 9

Flourochrome

Question 10

What is extravascular haemolysis?

Answer 10

Red cells taken up by reticuloendothelial system (liver and spleen mainly)

Question 11

What is intravascular haemolysis?

Answer 11

Red cells destroyed within circulation

Question 12

Describe extravascular red cell destrucion?

Answer 12

Commoner
Hyperplasia at site of destruction
Release of protoporphyrin

Question 13

Which is more likely to be life threatening, intra or extra vascular haemolysis?

Answer 13

Intra

Question 14

Why is intravascular so bad?

Answer 14

Red cells spill their contents into circulation

Question 15

What are the 4 potential problems that can arise from intravascular haemolysis?

Answer 15

1. Haemoglobinaemia (free Hb in circulation)
2. Methaemalbuminaemia
3. Haemoglobinuria (pink urine, turns black on standing)
4. Haemosiderinuria

Question 16

What are causes of intravascular haemolysis?

Answer 16

ABO incompatible blood transfusion
G6PD deficiency
Severe falciparum malaria (blackwater fever)
PNH,PCH (rare)

Question 17

What are causes of extravascular haemolysis?

Answer 17

Pretty much all other causes of haemolysis

Question 18

What are investigations for haemolysis?

Answer 18

Confirm haemolytic state.
FBC (+blood film)
Reticulocyte count
Serum unconjugated biliruben
Serum haptoglobins
Urinary urobilinogen

Question 19

Name 4 things that should be looked for on blood film?

Answer 19

Red cell fragments
Spherocytes
Heinz bodies
Sickle cells

Question 20

Name 1 specialist test for haemolysis?

Answer 20

Direct Coombs’ test

Question 21

What are 4 classifications based on site of red cell defect?

Answer 21

1. Premature destruction of normal red cells (immune or mechanical)
2. Abnormal cell membrane
3. Abnormal red cell metabolism
4. Abnormal haemoglobin

Question 22

What are two types of autoimmune haemolysis?

Answer 22

Warm (IgG)

Cold (IgM)

Question 23

What are types of warm (IgG)?

Answer 23

Idiopathic
Autoimmune (SLE)
Lymphoprolifrative disorders (CLL)
Drugs (penicillin)
Infections

Question 24

What are types of cold (IgM)?

Answer 24

Idiopathic
Infections (EBV, Mycoplasma)
Lymphoproliferative disorders

Question 25

What does a Coomb's test do?

Answer 25

Identifies antibody (and complement) bound to own red cells

Question 26

What are two types of Alloimmune haemolysis?

Answer 26

``` Immune response (antibody produced) Passive transfer of antibody ```

Question 27

What is Immune response alloimmune haemolysis?

Answer 27

Haemolytic tranfusion reaction Immeadiate, (IgM) predominantly intravascular Delayed (IgG) predominantly extravascular

Question 28

What is passive transfer to antibody alloimmune haemolysis?

Answer 28

Haemolytic disease of the newborn RhD ABO incompatibility Others e.g. anti-Kell

Question 29

What are causes of acquired haemolysis?

Answer 29

``` Disseminated intravascular coagulation Haemolytic uraemic syndrome (e.g. E.coli 0157) TTP leaking heart valve Infectious e.g. malaria ```

Question 30

What is MAHA?

Answer 30

Mechanical valve related Microangiopathic haemolytic anaemia - red cell fragmentation as a result of mechanical (extrinsic damage)

Question 31

When are microspherocytes seen?

Answer 31

In burns related haemolysis

Question 32

What are membrane defect causes of haemolysis?

Answer 32

``` Liver disease (Zieve's syndrome) Vitamin E deficiency paroxysmal Nocturnal haemoglobinuria ```

Question 33

What is seen in Zieve's syndrome?

Answer 33

Anameia polychromatic macrocytes Irregular contracted cells

Question 34

What are genetic causes of haemolysis?

Answer 34

Reduced membrane deformability Increased transit time through spleen Oxidant environment in spleen causes extravascular red cell destruction Hereditary spherocytosis