Hemolytic anemia natural history, complications and prognosis

In general, the natural history, complications, and prognosis depend on the underlying cause of hemolytic anemia. Some types of hemolytic anemia have a transient course with few complications and excellent prognosis. Some types of hemolytic anemia have a lifelong course with many complications and poor prognosis.

The natural history depends on the etiology of the hemolytic anemia.

• Drug-induced hemolytic anemia: This tends to be transient, if the etiology is identified. Once the drug is introduced, the hemolysis typically begins within a few days. Once the offending agent is discontinued, the hemolysis begins to abate. The course is usually mild. There are typically no long-term complications from this type of hemolysis. Serologic tests, such as the direct antiglobulin test, or Coomb’s test, can persist despite clinical resolution of symptoms.
• Autoimmune hemolytic anemia: This can have a lifelong course if the etiology is not identified. This can have an unpredictable course of relapses^[1] and remissions.
• Warm autoimmune hemolytic anemia in children: This has a self-limited course when treated with steroids.^[1] Steroids usually result in a rapid remission, especially if a high dose or induction dose is used. Relpases are unusual. The estimated mortality rate is 10-30%.
• Hereditary etiologies of hemolytic anemia: Such etiologies include G6PD deficiency, red blood cell membrane defects, or red blood cell enzyme defects. These tend to manifest with lifelong symptoms, as these are difficult to cure. Patients with these types of hemolytic anemia have lifelong risk.
• Cold agglutinin disease: This condition results in hemolysis in the presence of cold temperatures. The hemolysis begins upon exposure to cold then abates after cold temperatures are no longer present. Post-infection cold agglutinin disease typically lasts for weeks to months then resolves. Serological tests such, as the Donath-Landsteiner antibody, can persist despite clinical resolution of the hemolytic anemia.^[2]

The complications depend on the specific type of hemolytic anemia.

• Cardiovascular collapse: This refers to failure of the heart to produce a sufficient blood pressure to maintain normal homeostasis and oxygen delivery. This can lead to death from hypoxia and hypoxemia within a short period of time.
• Exacerbation of cardiopulmonary conditions: Hemolytic anemia can result in high-output cardiac failure, which refers to the inability of the circulatory system to meet the demands of exercising tissue, despite a high cardiac output. Hemolytic anemia can also exacerbate lung disease, since the capillary beds in the pulmonary circulation function to load oxygen onto hemoglobin for delivery to tissue beds.
• Exacerbation of neurologic conditions: Hemolytic anemia can contribute to cerebrovascular disease, or strokes, since the brain requires oxygen for survival of neurons.
• Myocardial infarction: Myocardial infarction, or heart attack, occurs if the anemia is severe such that the oxygen-carrying capacity is reduced to the coronary tissue. For this reason, patients with coronary artery disease should be transfused packed red blood cells if hemoglobin is less than 8 g/dl, compared to the conventional threshold of 7 g/dl for the general population.
• Transfusion dependence: This occurs when a patient requires repeated transfusions with packed red blood cells in order to maintain hemoglobin within an acceptable range, such as greater than 7 g/dl. Complications of transfusion include:
  • Transfusion-associated circulatory overload (TACO)^[3] For this reason, a restricted transfusion strategy is preferred over a liberal strategy.^[4]
  • Transfusion-related acute lung injury (TRALI)^[3]
  • Iron overload, or hemosiderosis
  • Transfusion reaction due to ABO blood group incompatibility

The outcome depends on the type and cause of hemolytic anemia.

• Drug-induced hemolytic anemia: The prognosis of this type of anemia is typically favorable if the offending agent is discontinued.
• Cold agglutinin disease: This has a generally good prognosis. Patients typically survive for many years. In the case of an associated lymphoma, the prognosis can be much worse depending the type of lymphoma.^[1]

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