Autoimmune hemolytic anemia natural history, complications and prognosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Assosciate Editor(s)-In-Chief: Prashanth Saddala M.B.B.S; Shyam Patel [2]

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Natural History

The natural history of autoimmune hemolytic anemia is self-limited in children if treated with corticosteroids. Most children respond very well to steroids and can lead normal lives without frequent relapses or recurrences. After recovery from the initial hemolytic episodes, it is unlikely that children will relapse. In older children, autoimmune hemolytic anemia can be chronic.

Complications

• Infection: This is a serious concern in patients on long-term immunosuppressant therapy, especially in very young children (less than two years). Infections occur due to impaired cell-mediated and humoral immunity. Different immunosuppressive agents have different infectious complication profiles. For example, patients on rituximab can experience the rare but highly lethal infection with JC virus, which causes progressive multifocal leukoencephalopathy. Severe infections can result in death.
• Thrombosis: Patients with autoimmune hemolytic anemia are at higher risk for thrombosis. Thrombosis is more likely to occur in the active phase of hemolysis, such as during a severe hemolytic episode. Anti-phospholipid antibodies are associated with the occurrence of thrombosis, as these antibodies bind to platelet membranes and induce thrombosis. Patients with autoimmune hemolytic who have a known history of thrombosis or are at high risk for thrombosis from other etiologies should begin anticoagulation.
• Iron overload: Autoimmune hemolytic anemia is frequently complicated by iron overload due to frequent red blood cell transfusions. In patients for whom steroids do not work, red blood cell transfusions can be an important temporizing measure to maintain the hemoglobin concentration with a safe range. For example, a typical hemoglobin threshold of 7g/dl is used when considering transfusion requirements. However, a major adverse effect of frequent transfusions is iron overload, as iron can deposit in a variety of organs and result in impaired organ function. For these reasons, it is best to address the underlying cause (immune activation) of autoimmune hemolytic anemia, rather than provide transfusional support in the long-term.
  • Hepatic iron overload: Iron deposition in the liver can be detected via T2 STAR magnetic resonance imaging MRI or by liver biopsy showing Prussian blue staining of hepatocytes. Iron deposition in the liver can result in symptoms of abdominal distension, bleeding, jaundice, edema, and portal hypertension. Treatment involves iron chelators such as deferoxamine, dereasirox, or deferiprone.
  • Cardiac iron overload: Iron deposition in the heart can be detected via echocardiogram showing diastolic dysfunction, electrocardiogram (EKG) showing low voltage complexes, T2 STAR magnetic resonance imaging MRI, or cardiac biopsy showing Prussian blue staining of hepatocytes. Iron deposition in the heart can result in symptoms of fatigue, shortness of breath, chest pain, edema, orthopnea, and paroxysmal nocturnal dyspnea. Treatment involves iron chelators such as deferoxamine, dereasirox, or deferiprone.
• End-organ damage from impaired oxygen delivery: The effects of severe anemia affect a variety of organs and tissues that rely heavily upon oxygen for energy metabolism. If hemoglobin decreases significantly, typically to values lower than 7g/dl, patients can experience impaired oxygen delivery and end-organ hypoxia. If hemoglobin decreases significantly, typically to values lower than 7g/dl, patients can experience impaired oxygen delivery and end-organ hypoxia.
  • Hypoxic brain injury: This is a rare but important complication of severe anemia. Low oxygen delivery to the brain as a result of autoimmune hemolytic anemia can result in ischemic injury to neurons and supporting tissue. This is functionally similar to cerebrovascular accident, or stroke, which is due to atherosclerotic or embolic blockage of the cerebral circulation. Patients can experience severe symptoms such as numbness, weakness, paralysis, and dysarthria, or slurred speech. Patients can have significant neurological impairment (including deficits in motor, sensory, cortical, and cerebellar function). Overall, the likelihood of hypoxic brain injury due to autoimmune hemolytic anemia is very low.
  • Myocardial injury: Autoimmune hemolytic anemia can result in impaired oxygen delivery to the cardiac tissue. Myocardial infarction can result from poor oxygen content in the coronary circulation, which is functionally similar to having ischemia due to blockage by an atherosclerotic plaque. Patients can experience severe symptoms such as shortness of breath, fatigue, and decreased exercise tolerance. Anemia is associated with poor outcomes. Patients can have long-term complications such as congestive heart failure.
  • High-output cardiac failure: Hemolytic anemia can also be associated with high-output cardiac failure, in which the ejection fraction and cardiac output are higher than normal. This is a manifestation of impaired oxygen delivery at the tissue level, for which the body compensated by increasing the circulatory output in an attempt to deliver more oxygen to tissues. High-output cardiac failure can lead to congestive heart failure.

Prognosis

The prognosis of autoimmune hemolytic anemia is variable and depends on the severity of the immune activation. In the early 2000s, studies reported a 10-year survival of 73%. In the current era, the survival is likely better. The mortality rate is 10-30%. Patients with concurrent immune thrombocytopenia purpura have a higher mortality rate. This condition is known as Evan's syndrome.

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