Clinical Manifestations And Treatment Of Autoimmune Hemolytic Anemia
Penicillins Can Cause Autoimmune Hemolytic Anemia
Autoantibodies develop against the erythrocytes. The antibody may agglutinate the red cells at 37oC (warm antibody) or at lower temperatures (cold antibody). Warm antibodies generally belong to IgG class whereas cold antibodies are IgM. In the warm antibody type, hemolysis takes place extravascularly in the spleen, while in the cold antibody type hemolysis occurs intravascularly or in the liver. Warm antibody type may vary in its course from mild chronic anemia to explosive and life-threatening hemolytic crises.
Causes of autoimmune hemolytic anemia are as follows:
Warm antibody type
Cold antibody type
1. Idiopathic (primary)
2. Drugs, e.g, Penicillin and methyldopa
Infections by viruses eg, E.B. virus and mycoplasma infection
3. Systemic lupus erythematosus and other collagen disorders
Drugs e.g stibophen
4. Lymphomas and chronic lymphatic leukemia
Chronic lymphatic leukemia
Renal Failure In Autoimmune Hemolytic Anemia
The majority of cases present with symptoms like anemia, jaundice and splenomegaly. In secondary autoimmune Hemolytic Anemia, features of the underlying disorder may be evident. Acute massive hemolysis with shock and renal failure may develop in some cases.
Hemolytic anemia of the cold antibody type may give rise to two clinical syndromes:
- Cold agglutinin syndrome and
- Paroxysmal cold hemoglobinuria.
Cold agglutinin syndrome occurs in the older patients and presents with acrocyanosis, Raynaud’s phenomenon, gangrene of finger tips and a mild chronic hemolytic anemia. In paroxysmal cold hemaglobinuria, sudden hemolysis with hemoglobinuria develops on exposure to cold.
The peripheral blood film shows marked anisopoikilocytosis, polychromasia, spherocytosis and increase in reticulocytes. Neutrophil leucocytosis is common. Rarely platelets may be reduced due to the development of antibodies against them (Evan’s syndrome). The antibodies present on erythrocytes can be demonstrated by the direct Coomb’s test and free antibodies in the serum can be identified by the indirect Coomb’s test. The thermal characteristics are demonstrable by suitable tests.
In secondary hemolytic anemia, treatment is directed towards the underlying cause. If blood transfusion is necessary, properly cross-matched erythrocytes are given. Majority of cases of primary Autoimmune hemolytic Anemia responds to prednisolone in a daily dose of 1-2 mg/Kg body weight. Once the acute episodes are controlled, the dose should be tapered off but the maintenance doses may have to be continued for prolonged periods. In cases where steroids fail or the maintenance dose is high, splenectomy has to be considered. If erythrocyte destruction can be demonstrated in the spleen by isotopic methods, such cases benefit promptly by splenectomy. In the others, although the response is unpredictable, 33-50% still derive benefit.
Immunosuppressive drugs like azathioprine (2-3 mg/Kg body weigh) or cyclophosphemide (1-2 mg/Kg body weight) are indicated if steroids are ineffective.
In cold antibody type, if the hemolysis is mild, only general measures such as avoidance of cold may be necessary. If transfusions are necessary, the blood should be warmed to body temperature before infusion. Steroids and splenectomy are less effective in this type, compared to warm antibody type of Autoimmune hemolytic anemia.
© 2014 Funom Theophilus Makama