Autoimmune hemolytic anemia (AIHA) is a type of hemolytic anemia where the body's immune system attacks its own red blood cells (RBCs), leading to their destruction (hemolysis). Antibodies and associated complement system components become fixed onto the RBC surface. These antibodies can be detected with the direct antiglobulin test, also known as the direct Coombs test. AIHA can also be induced by several drugs including methyldopa and fludarabine.

Autoimmunity must not be confused with alloimmunity.

Classification

Haemolysis can be intravascular or extravascular.

Intravascular haemolysis
Red blood cell lysis occurs in the circulation as a result of activation of the complement system cascade. Extravascular haemolysis
Red Blood Cells that are coated with antibodies are specifically recognised in the reticuloendothelial system and destroyed by macrophages.

Subtypes

Warm antibody autoimmune hemolytic anemia

• Idiopathic
• Systemic lupus erythematosus
• Evans' syndrome (antiplatelet antibodies and haemolytic antibodies)
• Chronic lymphocytic leukemia
• Drugs (methyldopa)

Cold antibody autoimmune hemolytic anemia

• Idiopathic cold hemagglutinin syndrome
• Infectious mononucleosis
• Paroxysmal cold hemoglobinuria (rare)
• Lymphoma

Mixed-type autoimmune hemolytic anemia

Laboratory findings

• Positive direct Coombs test
• Anaemia

See also

• Haematology
• Haemolytic anaemia

References

• eMedicine

External links

• Case report of Autoimmune Hemolytic Anemia with typical laboratory findings. Clinical Cases and Images.