Autoimmune hemolytic anemia

Immune hemolytic anemia can be either isoimmune or autoimmune. Autoimmune hemolytic anemias (AIHA) consist of group of disorders whose common characteristics are the presence of an antibody which in turn causes short red blood cell (RBC) life. The rate and site of hemolysis and hence the clinical manifestations depends on the type of antibody attached and its propensity to fix complement. Antibodies of the IgG class are most commonly responsible for AIHA in children. Rh erythrocyte antigen is involved in more than 70% of cases. Since the antibody has its maximal activity at 37 degrees C, the resultant hemolysis is called warm antibody induced hemolytic anemia. This is a severe life threatening condition, the clinical features are: sudden onset of pallor, jaundice and dark urine. The cornerstone of diagnosis is a positive Coomb's antiglobulin test in the presence of hemolysis. Coomb's test has false negative and false positive rates in about 2-4% and 8% of all cases respectively. The modalities for treatment of warm AIHA include blood transfusion, steroid therapy, intravenous gammaglobulin, plasma-pheresis and splenectomy. The choice depends on the severity of the disease and child's response to therapy.