Hyperhaemolysis caused by anti-HI antibodies in a patient with myelodysplastic syndrome following a first ever red cell transfusion.

Background: Hyperhaemolysis is a rare and life-threatening delayed haemolytic transfusion reaction characterised by complement-mediated destruction of both host and transfused red cells. It is well recognised as a complication of transfusion in patients with haemoglobinopathies and has occasionally been described in haematological malignancy and anaemia of chronic disease. Anti-HI antibodies are usually clinically insignificant but have rarely been associated with haemolytic transfusion reactions, including cases of hyperhaemolysis in sickle cell disease.