Hyperhemolysis syndrome: A relative contraindication for transfusion

Division of Transfusion Medicine, Department of Pathology, University of Virginia, Charlottesville, Virginia Hyperhemolysis syndrome is a form of atypical hemolytic transfusion reaction (HTR). It is characterized by a significant drop in hemoglobin (Hb) after seemingly compatible red blood cell transfusions, suggesting destruction of both transfused and autologous red blood cells. Its pathophysiology is not well understood, and a serologic cause is often not identified. In contrast, delayed HTRs are typically characterized by a positive direct antiglobulin test (DAT), suggesting that the patient’s red blood cells are coated by immunoglobulin G and/or complement components and by the appearance of previously undetected red blood cell alloantibody or antibodies that developed from a secondary anamnestic response; however, autologous red cells are not destroyed.