AUTOIMMUNE HAEMOLYTIc ANAEMIA

Summary

Autoimmune hemolytic anemia (AIHA) occurs when the immune system attacks and destroys red blood cells, leading to anemia. It is classified into two types: warm AIHA, caused by IgG antibodies, and cold AIHA, caused by IgM antibodies. Warm AIHA primarily affects the spleen, while cold AIHA can cause complications in both the liver and blood vessels. Symptoms include fatigue, jaundice, and shortness of breath. Diagnosis is confirmed with laboratory tests like the direct antigen test. Treatment varies, with corticosteroids for warm AIHA and plasmapheresis for severe cold AIHA cases.

Takeaways

• 😀 Autoimmune hemolytic anemia (AIHA) occurs when the body's antibodies mistakenly target and destroy red blood cells, leading to anemia.
• 😀 AIHA can be idiopathic (without a known cause), but can also be triggered by medications or underlying diseases like lupus or lymphoma.
• 😀 Red blood cells (RBCs) are typically produced in the bone marrow and live for 100-120 days, after which they are recycled by macrophages in the spleen or liver.
• 😀 AIHA is classified into two types: warm (more common) and cold, based on the temperature at which red blood cells are targeted.
• 😀 Warm AIHA involves IgG antibodies that target RH antigens on RBCs, leading to their destruction by macrophages in the spleen.
• 😀 Cold AIHA involves IgM antibodies targeting RBC antigens like I and P, and hemolysis occurs via the classical complement pathway, typically in the liver.
• 😀 Hemolysis leads to the release of lactate dehydrogenase (LDH) and hemoglobin from RBCs, causing an increase in these substances in the blood.
• 😀 In cases of intravascular hemolysis, hemoglobin can spill into the urine, causing hemoglobinuria, and potentially lead to kidney damage.
• 😀 Symptoms of AIHA include fatigue, shortness of breath, jaundice (yellowing of the skin), and potentially spleen or liver enlargement.
• 😀 Diagnosis of AIHA involves laboratory tests, including the direct antiglobulin test (Coombs test), which identifies antibodies bound to RBCs.
• 😀 Treatment of warm AIHA typically includes steroids or splenectomy, while cold AIHA may require plasmapheresis to remove harmful IgM antibodies.

Q & A

What is autoimmune hemolytic anemia (AIHA)?

Autoimmune hemolytic anemia is a condition where the immune system produces antibodies that target and destroy a person's own red blood cells, leading to a lower-than-normal number of red blood cells (anemia).

What are the two main types of autoimmune hemolytic anemia (AIHA)?

The two main types of AIHA are warm autoimmune hemolytic anemia and cold autoimmune hemolytic anemia, distinguished by the temperature at which hemolysis (destruction of red blood cells) occurs.

How does warm autoimmune hemolytic anemia differ from cold autoimmune hemolytic anemia in terms of antibody involvement?

Warm AIHA involves IgG antibodies that react with the Rh antigen on red blood cells, whereas cold AIHA involves IgM antibodies that target antigens like I and P on red blood cells.

What is the primary mechanism behind warm autoimmune hemolytic anemia?

In warm AIHA, IgG antibodies bind to antigens on red blood cells, triggering antibody-dependent cell-mediated cytotoxicity. This leads to the destruction of red blood cells, primarily by macrophages in the spleen.

How does cold autoimmune hemolytic anemia lead to red blood cell destruction?

In cold AIHA, IgM antibodies activate the classical complement pathway, which results in the formation of the membrane attack complex (MAC) that destroys red blood cells, often in the liver.

What are the common symptoms of autoimmune hemolytic anemia?

Common symptoms include fatigue, shortness of breath, jaundice (yellowing of the skin), splenomegaly (enlarged spleen), and in severe cases, a hemolytic crisis with rapid anemia and multi-organ failure.

How is autoimmune hemolytic anemia diagnosed?

Diagnosis involves laboratory tests, including a Direct Antigen Test (Coombs test), which detects antibodies bound to the surface of red blood cells. Positive results can indicate warm or cold AIHA based on the type of antibody present.

What causes warm autoimmune hemolytic anemia?

Warm AIHA is most often idiopathic (without a known cause), but it can also be triggered by viral infections, autoimmune diseases like lupus, lymphomas, leukemias, and certain medications such as penicillin.

What causes cold autoimmune hemolytic anemia?

Cold AIHA can be caused by infections (especially viral ones like pneumonia and mononucleosis), as well as underlying conditions such as leukemia and lymphomas.

What are the treatment options for warm and cold autoimmune hemolytic anemia?

For warm AIHA, the first-line treatment is steroids, with splenectomy or immunosuppressive medications for refractory cases. Cold AIHA may not require treatment unless anemia is severe, in which case plasmapheresis can be used to remove harmful antibodies.