Autoimmune Hemolytic Anemias

This chapter reviews autoimmune hemolytic anemias (AIHA) which includes a group of disorders where autoantibodies are directed against red blood cell (RBC) membrane antigens. This results in shortened RBC survival through activation of the complement system and removal within the reticuloendothelial system. AIHA are classified as: warm autoimmune hemolytic anemia (WAIHA), cold agglutinin disease (CAD), mixed type AIHA, paroxysmal cold hemoglobinuria (PCH) and drug-induced hemolytic anemia. The diagnosis of AIHA is dependent on the clinical features and the serologic work-up, primarily the direct antiglobulin test. In AIHAs, the degree of hemolysis depends on the antibody class and characteristics such as concentration and antigen affinity, ability to fix complement and thermal amplitude. The presence of anti-erythrocyte autoantibodies does not always cause hemolysis and thus anemia. When hemolysis is of significant degree, anemia, jaundice and splenomegaly can occur. The clinical laboratory tests should include a complete blood count, reticulocyte count, serum bilirubin level and serum lactic dehydrogenase level. © 2009 Elsevier Inc. All rights reserved.

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Author Beth H. Shaz Pathology