Autoimmune Haemolytic Anaemia

Key points

• Autoimmune haemolytic anaemia (AIHA) is divided into 'warm' and 'cold' types, according to the temperature at which the antibodies best cause haemolysis
• Warm AIHA: antibody usually IgG; haemolysis best at body temperature; typically extravascular (spleen)
• Causes of warm AIHA: idiopathic, autoimmune disease (e.g. SLE), neoplasia (e.g. lymphoma, CLL), drugs (e.g. methyldopa)
• Cold AIHA: antibody usually IgM; haemolysis best at 4°C; complement-mediated and more commonly intravascular
• Causes of cold AIHA: neoplasia (e.g. lymphoma), infections (e.g. mycoplasma, EBV)