Haemolytic Anaemia

Question 1

What is haemolytic anaemia?

Answer 1

Anaemia related to reduced RBC lifespan. There is no blood loss or haematinic deficiency

Question 2

What are the haematological results of a compensated haemolytic anaemia?

Answer 2

• Normal Hb
• Raised reticulocytes,
• Raised unconjugated bilirubin.

Question 3

What are the haematological results of an (uncompensated) haemolytic anaemia?

Answer 3

• Low Hb,
• Raised reticulocytes,
• Raised bilirubin,
• Palpable spleen.

Question 4

Name and describe an example of a congenital haemolytic anaemia

Answer 4

Hereditary spherocytosis.
It is an autosomal dominant disease where the RBCs are spherocytic and polychromatic. It presents with jaundice and splenomegaly

Question 5

What is the possible treatment for hereditary spherocytosis?

Answer 5

Splenectomy and hyposplenic prophylaxis. Patients who are hyposplenic present with Howell Jolly bodies.

Question 6

What is hypospenic state?

Answer 6

Occurs due to splenectomy and resultant encapsulated organisms infections such as pneumococcus, meningococcus and haemophilus. Treated with immunisations and long term penicillin V

Question 7

Name inherited haemolytic anaemias

Answer 7

1. Hereditary spherocytosis,
2. Haemoglobinopathies (sickle cell and thalassaemia
3. Abnormalities of RBC enzymes (G6PD deficiency, Pyruvate kinase def anaemia)

Question 8

What are the different defective enzymes pathways that result in anaemias

Answer 8

1. Pyruvate kinase deficiency anaemia. Glycolysis pathway - Pyruvate kinase deficiency results in ATP depletion causing RBCs to haemolyse. Autosomal recessive.
   2, Pentose phosphate pathways. X-linked recessive. Where a deficiency in glucose 6 phosphate dehydrogenase results in depleted levels of NADPH (normal function is to protect against oxidative stress)

Question 9

What are the clinical features of enzyme deficiencies causing haemolytic anaemia

Answer 9

1. Pyruvate kinase def anaemia - Chronic, extravascular haemolytic anaemia. because RBCs haemolyse as they are depleted of ATP.
2. Glucose 6 phosphate dehydrogenase def anaemia - acute episodic intravascular haemolysis. Normally asymptomatic but get episodes of acute haemolysis when exposured to oxidative stress (eg, consumption of favamines, or certain drugs like antimalarials or sulphonamides)

Question 10

What are the different types of acquired haemolytic anaemias?

Answer 10

Autoimmune - Warm types (IgG) and cold type (IgM)
Isoimmune - haemolytic disease of the newborn.
Non immune - fragmentation haemolysis

Question 11

What are some causes of fragmentation haemolysis?

Answer 11

• Involved mechanical breakdown of cells. Examples include:
• Malfunctioning mechanical heart valve,
• Haemolytic uraemic syndrome,
• Disseminated intravascular dissemination

Question 12

What is cold autoimmune haemolytic anaemia?

Answer 12

IgM autoantibodies and complement targeted against RBCs
- Can be caused by mycoplasma infections, idiopathic or associated with lymphoproliferative disorders.
- Blood film shows agglutination

Question 13

Describe features of warm autoimmune haemolytic anaemia

Answer 13

IgG autoantibodies with/without complement attack against on RBC.
- Can be idiopathic, caused by other autoimmune disease, lymphoproliferative disorders or drug induced.
- Blood film will show polychromatic spherocytes

Question 14

Describe drug induced autoimmune haemolytic anaemia

Answer 14

Drug acts as hapten (molecule that illicit an immune response) which usually causes mild haemolysis. If the drug and antibody form an immune complex then it causes severe haemolysis

Question 15

Describe a direct coombs test?

Answer 15

Anti-human immunoglobulin is used to react with antibodies on the red blood cell surface. If positive then it indicates AIHA and HDN.

Question 16

Describe an indirect coombs test

Answer 16

Patients plasma is mixed with donor blood. Antihuman immunoglobulin is then added to detect the presence of RBC antibodies

Question 17

Whats the treatment for autoimmune haemolytic anaemia?

Answer 17

Cold (IgM) - Self-limiting mycoplasma infection and keep patient warm.

Warm (IgG) - Stop any drugs then give steroids, immunosuppression and splenectomy

Question 18

Describe haemolytic disease of the new born

Answer 18

This occurs when a Rhesus negative mother has a Rhesus positive baby. Some of the foetal RBCs enter the maternal circulation, stimulating an immune response. The resulting IgG antibodies passes through the placenta and attacks the baby.

Question 19

Describe features of hereditary spherocytosis

Answer 19

• Autosomal dominant condition, common in northern europeans where there is reduced RBC survival as they are destroyed by the spleen