Haemolytic anaemia

Question 1

What is haemolysis?

Answer 1

Premature red cell destruction i.e. shortened red cell survival

Question 2

What is compensated haemolysis?

Answer 2

Increased red cell destruction compensated by increased red cell production i.e. Hb Maintained

Question 3

What is haemolytic anaemia?

Answer 3

Increased rate of red cell destruction exceeding bone marrow capacity for red cell production i.e. Hb Falls

Question 4

Is haemolytic anaemia an example of compensated or decompensated haemolysis?

Answer 4

Decompensated haemolysis since there is red cell destruction and the Hb falls.

Question 5

What are the many diverse causes of haemolytic anaemia?

Answer 5

Hereditary or acquired

Classified based on the location of the haemolysis - intravascular or extravascular

Autoimmune (Coombs positive) or nonautoimmune (Coombs negative)

Question 6

What are examples of inherited haemolytic anaemias?

Answer 6

Hereditary spherocytosis

Hereditary elliptocystosis

Thalassaemia

Sickle cell anaemia

G6PD deficiency

Question 7

What are examples of acquired haemolytic anaemias?

Answer 7

Autoimmune haemolytic anaemia

Alloimmune haemolytic anaemia (transfusion reactions and haemolytic disease of the newborn)

Paroxysmal nocturnal haemoglobinuria

Microangiopathic haemolytic anaemia

Prosthetic valve related haemolysis

Question 8

Why are red cells susceptible to damage?

Answer 8

Biconcave shape

Limited metabolic reserve, means it relies exclusively on glucose for energy (no mitochondria)

Can’t generate new proteins once in circulation (no nucleus)

Question 9

What is intravascular haemolytic anaemia?

Answer 9

Intravascular haemolysis occurs in the bloodstream, resulting in the release of haemoglobin into the bloodstream.

Question 10

What are the causes of intravascular haemolytic anaemia?

Answer 10

Intrinsic cell injury e.g. G6PD deficiency

Cold autoimmune haemolytic anaemia

Paroxysmal nocturnal haemoglobinuria and acute transfusion reactions

Mechanical injury - microangiopathic haemolytic anaemia and cardiac valves.

Question 11

What is extravascular haemolytic anaemia?

Answer 11

Extravascular haemolysis occurs in the reticuloendothelial system (spleen and liver)

It is not associated with dramatic release of free haemoglobin into the circulation

Question 12

What are the causes of extravascular haemolytic anaemia?

Answer 12

Abnormal red cells e.g. sickle cell anaemia and hereditary spherocytosis

Warm autoimmune haemolytic anaemia

Question 13

What is compensated haemolytic anaemia (haemolysis)?

Answer 13

Increased red cell destruction compensated by increased red cell production.

Therefore Hb maintained.

Question 14

What is decompensated haemolytic anaemia (haemolysis)?

Answer 14

Increased rate of red cell destruction which exceeds the bone marrow capacity for red cell production.

Therefore Hb falls.

Question 15

What are the clinical features of haemolytic anaemia (haemolysis)?

Answer 15

Depends on underlying cause and whether the anaemia is compensated but some common features are:

• Anaemia due to reduction in circulating red blood cells.
• Splenomegaly due to spleen becomes filled with destroyed red blood cells.
• Jaundice as bilirubin is released during the destruction of red blood cells.

Question 16

Investigations for haemolytic anaemia?

Answer 16

Confirm haemolytic state: FBC (+blood film), reticulocyte count, serum unconjugated bilirubin.

Blood film:
- Membrane damage – spherocytes
- Mechanical damage – red cell fragments
- Oxidative damage due to G6PD deficiency – Heinz bodies
- Others e.g HbS (sickle cell)

Specialist investigations e.g. direct Coomb’s test (positive in autoimmune haemolytic anaemia)

Question 17

What are spherocytes?

Answer 17

Spherical red blood cells without an area of central pallor on microscopy and are usually slightly smaller in size than the average red cell.

Presence of abundant spherocytes in the peripheral blood smear suggests either hereditary spherocytosis (HS) or autoimmune hemolytic anemia (AIHA).

Question 18

What is G6PD deficiency?

Answer 18

An inherited condition. It is when the body doesn’t have enough of an enzyme called G6PD (glucose-6-phosphate dehydrogenase).

This enzyme helps red blood cells work properly. A lack of this enzyme can cause haemolytic anaemia.

Question 19

What main food group should those with G6PD deficiency avoid in particular?

Answer 19

Legumes (such as beans, peas, lentils, or peanuts)

Fava beans is a common example.