AUTOIMMUNE HEMOLYTIC ANEMIA
Autoimmune hemolytic anemia is a rare red blood cell disorder and an immune disorder. It happens when the body produces antibodies that destroy the red blood cells.
Hemolytic anemia develops when there are not enough red blood cells because the body destroys them sooner than it should. Red blood cells carry oxygen around the body.
Autoimmune hemolytic anemia (AIHA), or immune hemolytic anemia, happens when the immune system does not work properly. It mistakes red blood cells for unwanted substances and attacks them, causing them to die early. This leaves a person without enough red blood cells.
Normally, red blood cells live in the body for 100 to 120 days. However, in severe cases of AIHA, the cells may remain only for a few days.
In children, it is a rare condition that is usually temporary. In some adults, however, AIHA can be a long-term condition that returns frequently.
AIHA can develop rapidly or over time.
In about half of cases, the cause of autoimmune hemolytic anemia cannot be determined (idiopathic or primary). This condition can also be caused by or occur with another disorder (secondary) or rarely, occur following the use of certain drugs (such as penicillin) or after a person has a blood and marrow stem cell transplant. Secondary causes of autoimmune hemolytic anemia include:
- Autoimmune diseases, such as lupus
- Chronic lymphocytic leukemia
- Non-Hodgkin’s lymphoma and other blood cancers
- Epstein-Barr virus
- Mycoplasma pneumonia
Symptoms and Signs
Autoimmune hemolytic anemia typically produces an anemia of rapid onset that may be life-threatening. Patients complain of fatigue and dyspnea and may present with angina pectoris or heart failure. On examination, jaundice and splenomegaly are usually present.
Initial treatment consists of prednisone, 1–2 mg/kg/day orally in divided doses. Patients with DAT-negative and DAT-positive autoimmune hemolysis respond equally well to corticosteroids. Transfused red blood cells will survive similarly to the patient’s own red blood cells. Because of difficulty in performing the cross-match, possible “incompatible” blood may need to be given. Decisions regarding transfusions should be made in consultation with a hematologist and a blood bank specialist.
Death from cardiovascular collapse can occur in the setting of rapid hemolysis. In patients with rapid hemolysis, therapeutic plasmapheresis should be performed early in management to remove autoantibodies. If prednisone is ineffective or if the disease recurs on tapering the dose, splenectomy should be considered, which may cure the disorder.
Patients with autoimmune hemolytic anemia refractory to prednisone and splenectomy may also be treated with a variety of agents. Treatment with rituximab, a monoclonal antibody against the B cell antigen CD20, is effective in some cases. The suggested dose is 375 mg/m2 intravenously weekly for 4 weeks. Rituximab is used in conjunction with corticosteroids as initial therapy in some patients with severe disease.
Danazol, 400–800 mg/day orally, is less often effective than in immune thrombocytopenia but is well suited for long-term use because of its low toxicity profile. Immunosuppressive agents, including cyclophosphamide, vincristine, azathioprine, mycophenolate mofetil, alemtuzumab (an anti-CD52 antibody), or cyclosporine, may also be used. High-dose intravenous immune globulin (1 g/kg daily for 2 days) may be effective in controlling hemolysis.