It causes a microcytic anaemia and raised reticulocyte count.
Intravascular haemolysis is characterised by:
- low haptoglobin (as all used up trying to 'recycle' the broken down red cells)
- raised free plasma haemoglobin
- haemoglobuinuria: red-brown urine
- haemosiderinuria: once haptoglobin binding capacity is surpassed free Hb is filtered by the kidneys and can be detected in the urine in sloughed tubular cells using Prussian blue staining
Causes of intravascular haemolysis include:
- cold AIHA
- transfusion reaction
- G6PD (recall battle 28.4?)
- paroxysmal nocturnal haematuria (recall battle 27.6?)
- microangiopathic haemolytic anaemia (recall battle 38.6?)
- mechanical heart valves
Extravascular haemolysis may cause splenomegaly.
Causes of extravascular haemolysis include:
- warm AIHA (remember battle 39.7?)
- cold haemagglutination disease
- haemolytic disease of the newborn
Now to the second haem battle of the day...