Autoimmune hemolytics anemias (AIHA) are grossly divided up based on the type of antibody produced by the reaction. IgG antibodies which react with protein antigens of the surface of RBCs at body temperature are referred to as “warm agglutinins”. This accounts for approximately 80% of AIHA.
The etiology of warm agglutinin AIHA is variable with most cases being idiopathic. Conditions which may be associated with this disease are:
The etiology of warm agglutinin AIHA is variable with most cases being idiopathic. Conditions which may be associated with this disease are:
- viral infections
- secondary to autoimmune disease - eg. SLE
- secondary to lymphoproliferative disorders – CLL, Hodgkins
- drug induced – hapten mediated (eg PCN) vs true anitbody mediated (e.g. methyl dopa)
- allogenic blood transfusion
The diagnosis is based on the demonstration of autoimmune destruction using the Coombs test. With the DIRECT COOMBS, the RBCS of the patient are washed free of adherent proteins and are reacted with antiserum or monocloncal antibodies prepared against various immunoglobulins and complement.
Clinically the anemia tends to be symptomatic. On exam patients tend to be jaundice, pale and have mild-moderate splenomegaly.
Blood film is characterised by spherocytes.
The hallmark of treatment once the diagnosis is confirmed is corticosteroids (1mg/kg predisone). Options for refractory disease include splenoctomy and for those not able to tolerate / not wanting surgery…immunospupressive / cytotoxic therapy including azathoprine, cyclophosphamide, cyclosporin and rituximab.
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