Thanks to Dr. Rachel Kyung for an outstanding presentation on idiopathic autoimmune hemolytic anemia!

Teaching Points:

• The etiology of new anemia may be broken down into the categories of decreased RBC production, increased RBC destruction, or blood loss.
• Hemolysis may be caused by intrinsic red cell defects including:
  • Enzyme deficiencies (e.g. G6PD deficiency)
  • Hemoglobin defects (sickle cell disease, thalassemias)
  • Membrane defects (hereditary spherocytosis, PNH)
• Causes of hemolysis extrinsic to red cells include MAHA (TTP, HUS, DIC, prosthetic heart valves), transfusion reaction (ABO incompatibility), PNH, infections (malaria or clostridial sepsis), or autoimmune hemolysis.
• Cold agglutinin disease is caused IgM antibodies against RBC’s which activates the classical compliment system. It may be primary (idiopathic) or secondary to infection or lymphoproliferative disorders.
• Warm agglutinin disease is characterized by IgG directed against RBC’s which results in spherocytosis on peripheral smear. Etiology may be idiopathic or secondary to infection, autoimmune disease, lymphoprolipherative disorders (CLL) or medications. Treatement includes steroids or cytotoxic drugs and splenectomy in refractory cases. Diagnosis of both cold- and warm agglutinin disease is made by a positive Coombs test.
• Click here for a recent article discussion RBC transfusion in patients with autoimmune hemolytic anemia.