Paroxysmal cold haemoglobinuria

**Definition:** Paroxysmal cold hemoglobinuria is a very rare subtype of autoimmune haemolytic anaemia (AIHA), caused by the presence of cold-reacting autoantibodies in the blood and characterised by the sudden presence of hemoglobinuria, typically after exposure to cold temperatures. PCH is thought to account for at most 2-10% of cases of AIHA.