Autoimmune haemolytic anaemia

Question 1

Autoimmune haemolytic anaemia?

Answer 1

Autoimmune haemolytic anaemia (AIHA) may be divided in to ‘warm’ and ‘cold’ types:

• according to at what temperature the antibodies best cause haemolysis.
• It is most commonly idiopathic but may be secondary to a lymphoproliferative disorder, infection or drugs.
• AIHA is characterised by a positive direct antiglobulin test (Coombs’ test)

Question 2

Warm AIHA?

Answer 2

• In warm AIHA the antibody (usually IgG) causes haemolysis best at body temperature and haemolysis tends to occur in extravascular sites, for example the spleen.
• Management options include steroids, immunosuppression and splenectomy

Causes of warm AIHA

• autoimmune disease: e.g. systemic lupus erythematosus*
• neoplasia: e.g. lymphoma, CLL
• drugs: e.g. methyldopa

Question 3

Cold AIHA?

Answer 3

• The antibody in cold AIHA is usually IgM and causes haemolysis best at 4 deg C.
• Haemolysis is mediated by complement and is more commonly intravascular.
• Features may include symptoms of Raynaud’s and acrocynaosis. Patients respond less well to steroids

Causes of cold AIHA:

• neoplasia: e.g. lymphoma
• infections: e.g. mycoplasma, EBV

*systemic lupus erythematosus can rarely be associated with a mixed-type autoimmune haemolytic anaemia