Red cell disorders

Question 1

What is haemolytic anaemia?

Answer 1

Anaemia due to increased red cell destruction or increased erythropoiesis (which does not always proceed functional cells).

Question 2

What are the two membrane defect disorders?

Answer 2

Hereditary spherocytosis and hereditary elliptocytosis.

Question 3

What are the two enzymopathies?

Answer 3

Deficiencies in the hexose monophosphate shunt
-G6P dehydrogenase deficiency (G6PDD)
Deficiencies in the Emben-Myerhof pathways
-Pyruvate kinase disease

Question 4

Facts about hereditary spherocytosis

Answer 4

1. Most common haemolytic anaemia in Northern europeans
2. Usually autosomal dominant, variable expression
3. Can be carried on any chromosome except the sex chromosome.
4. Defects involved in vertical interactions.
5. Cells become increasing spherical.

Question 5

Clinical features of HS

Answer 5

Anaemia
Jaundice
Splenomegaly

Question 6

Laboratory findings of HS

Answer 6

Increased reticulocytes: 5-20%

Blood film shows microcytes

Question 7

Treatment and diagnosis of HS

Answer 7

Osmotic fragility test (how much fluid can enter the RBC before it bursts)- severe= not very much, normal= a lot
Splenectomy- main treatment- reduces no. of cells destroyed.
Folic acid given in severe cases to prevent folate deficiency.

Question 8

What part of the membrane does hereditary elliptocytosis affect?

Answer 8

Horizontal interactions: spectrin, protein 4.1 and glycophorin C
Most common is defects in alpha and beta spectrin- failure of heteredimers to associate into heterotetramers.

Question 9

What does the blood film of a patient with hereditary elliptocytosis show?

Answer 9

Elongated cells

Question 10

What does G6PD deficiency lead to?

Answer 10

Oxidative stress. This leads to Heinz body formation and extravascular haemolysis.

Question 11

Facts about G6PD deficiency.

Answer 11

Most common enzymopathy.
X-linked inheritance (usually just males affected).
At least 400 variants- point mutations and deletions.
Enzyme activity reduced/ deficient.
Provides resistance to malaria.
Red cells extremely susceptible to oxidative stress.

Question 12

Clinical features of G6PD deficiency.

Answer 12

Precipitated by infection, illness, drugs or Fava beans.
Acute haemolytic anaemia.
Rapid intravascular haemolysis.
Haemoglobinuria

Question 13

Laboratory findings of G6PD deficiency.

Answer 13

Heinz bodies
Bite cells and blister cells
Premature destruction of RBCs

Question 14

What is the treatment of G6PD deficiency.

Answer 14

Stop taking the drug or treat infection.

Question 15

Features of pyruvate kinase deficiency.

Answer 15

• Autosomal recessive
• Over 100 different mutations
• Anaemia
• Jaundice
• Gallstones

Question 16

Laboratory findings of pyruvate kinase deficiency.

Answer 16

• Cells are rigid
• Reduced haemoglobin levels
• Macrocytosis
• Poikilocytosis (abnormally shaped RBCs)
• Autohaemolysis increased

Question 17

Treatment of pyruvate kinase deficiency.

Answer 17

Splenectomy

Blood transfusions

Question 18

Examples of acquired haemolytic anaemias

Answer 18

Autoimmune
-warm antibody type
-cold antibody type
Alloimmune
-haemolytic transfusion reactions
-haemolytic disease of the newborn
-allografts

Question 19

What are autoimmune anaemias caused by and how are they diagnosed?

Answer 19

They are caused by antibodies produced to attack own cells,

They are diagnosed by a positive direct anti globulin test (Coombs test)