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Chapter 101. Hemolytic Anemias and Anemia Due to Acute Blood Loss (Part 15)

Severe acute AIHA can be a medical emergency. The immediate treatment almost invariably includes transfusion of red cells. This may pose a special problem because if the antibody involved is "unspecific," all the blood units crossmatched will be incompatible. In these cases it is often correct, paradoxically, to transfuse incompatible blood, the rationale being that the transfused red cells will be destroyed no less but no more than the patient's own red cells, and in the meantime the patient stays alive. Clearly this rather unique situation requires good liaison and understanding between the clinical unit treating the patient and. | Chapter 101. Hemolytic Anemias and Anemia Due to Acute Blood Loss Part 15 Severe acute AIHA can be a medical emergency. The immediate treatment almost invariably includes transfusion of red cells. This may pose a special problem because if the antibody involved is unspecific all the blood units crossmatched will be incompatible. In these cases it is often correct paradoxically to transfuse incompatible blood the rationale being that the transfused red cells will be destroyed no less but no more than the patient s own red cells and in the meantime the patient stays alive. Clearly this rather unique situation requires good liaison and understanding between the clinical unit treating the patient and the blood transfusion serology lab. Paroxysmal Cold Hemoglobinuria PCH PCH is a rather rare form of AIHA occurring mostly in children usually triggered by a viral infection usually self-limited and characterized by involvement of the so-called Donath-Landsteiner antibody. In vitro this antibody has unique serologic features it has anti-P specificity and binds to red cells only at a low temperature optimally at 4 C but when the temperature is shifted to 37 C lysis of red cells takes place in the presence of complement. Consequently in vivo there is intravascular hemolysis resulting in hemoglobinuria. Clinically the differential diagnosis must include other causes of hemoglobinuria Table 101-2 but the presence of the Donath-Landsteiner antibody will prove PCH. Active supportive treatment including blood transfusion is needed to control the anemia subsequently recovery is the rule. Cold Agglutinin Disease CAD This designation is used for a form of chronic AIHA that usually affects the elderly and has special clinical and pathologic features. First the term cold refers to the fact that the autoantibody involved reacts with red cells poorly or not at all at 37 C whereas it reacts strongly at lower temperatures.1 As a result hemolysis is more prominent the more the body is .