Haemolytic Anaemias

Question 1

What is a haemolytic anaemia

Answer 1

Abnormal breakdown (haemolysis) of red blood cells in blood vessels (intravascular haemolysis) or the spleen (extravascular haemolysis)

Question 2

What are the symptoms of haemolytic anaemia

Answer 2

Shortness of breath and fatigue

Chronic induced haemolysis leads to accumulation of bilirubin leading to jaundice and possible gallstones

Question 3

What complications are there of haemolytic anaemia

Answer 3

Massive actue haemolysis can cause cardiac arrest due to lack of O₂ delivery to tissues and hyperkalaemia (release of intracellular contents)

Overworking of red pulp of spleen can lead to splenomegaly

Question 4

What are the types of acquired haemolytic anaemias

Answer 4

Mechanical damage - eg. microangiopathic anaemia

Antibody damage - eg. autoimmune haemolytic anaemia

Oxidant damage

Heat damage

Enzymetic damage - eg. snake venom

Osmotic changes

Question 5

What is microangiopathic haemolytic anaemia, give some examples and what are the RBCs produced called

Answer 5

Group of haemolytic anaemias where red cells are damaged by phyiscal trauma.

Examples: cells getting snagged as they try passing through small vessels laden with fibrin strands, disseminated intravascular coagulation (DIC), RBCs can be damaged by shear stress produced by defective heart vavles

RBCs produced are schistocytes

Question 6

What are immune haemolytic anaemias and what are the types

Answer 6

Haemolytic anaemias resutling from infection, lymphoproliferative disorders and reactions to drugs

Classified as either warm or cold

Warm - IgG autoantiboides bind to epitopes on RBC membrane. Macrophages in spleen recognise and break down

Cold - IgM autoantibodies bind to epitopes, also complement fixed to the RBCs. IgM bind to multiple RBCs at more distal parts (colder parts), forming agglutinations . Macrophages in spleen recognise complement and break down

Question 7

What are the types of inherited haemolytic anaemias

Answer 7

Glycolysis defect - pyruvate kinase deficiency

Pentose-P pathway - G6PDH deficiency

Membrane protein - eg. hereditary spherocytosis

Haemoglobin defect - sickle cell

Question 8

What is pyruvate kinase deficiency and how does it cause haemolytic anaemia

Answer 8

PKD is an inherited disorder due to mutations in the PKLR gene meaning there is a deficiency in PK in erythrocytes/cells

As RBCs lack mitochondria they need PK for ATP production and without it cellular processes stop

Na/K ATPase pump is inhibited by lack of ATP so RBC loses K to plasma, causing water to move out of the cell causing them to shrink resulting in cellular death and haemolytic anaemia

Question 9

What is G6PDH deficiency and how does it cause haemolytic anaemia

Answer 9

G6PDH deficiency is X-linked recessive inborn error of metabolism.

G6PDH supplies reducing energy (NADPH). Without this the level of reduced glutathione decreases and the cell becomes susceptable to oxidative stress during infection or exposure to chemicals. This causes haemolytic anaemia

Question 10

What is hereditary spherocytosis and how does it cause haemolytic anaemia

Answer 10

It is an autosomal dominant disease resulting in abnormalities te RBC membrane proteins (spectrin, ankyrin, band 3, protein 4.2) which impedes ability of RC to change shape

This results in reduction in membrane surface area and spherocyte RBCs. These are less deformable and become trapped and damaged in the spleen resulting in decreased RBC lifespan and haemolytic anaemia