Delayed haemolytic transfusion reaction

• Caused by an exaggerated response to a foreign red cell antigen that the patient has been exposed to before
• Patients present with jaundice, anaemia, and fever, usually on day 5 post-transfusion

Transfusion-associated graft-versus-host disease

• Caused by donor blood lymphocytes attacking the recipient's bodyRare but carries a high risk of mortality

Iron overload

• Iron overload may be related to the pathophysiology of the condition (e.g. haemochromatosis) or iatrogenic (e.g. related to a blood transfusion or excess oral iron)
• There is no secretion pathway for iron and approximately 1 mg of iron is lost via gut mucosal cells
• Absorption of luminal iron is mediated by enterocytes, which respond to iron stores in the body
• The enterocyte is modulated via its transferrin receptor, which regulates transferrin uptake from the plasmaIn turn, the HFE protein modulates transferrin receptor activity
• Iron overload usually becomes an issue after 20 units have been given or if serum ferritin rises above 1000 µg/l
• Subcutaneous desferrioxamine is required regularly to lower iron levels