Autoimmune Hemolytic Anemia (AIHA)
Characteristics
Auto-immune hemolytic anemia (AIHA) is a rare immune disorder in which the immune system mistakes red blood cells as unwanted substances. This triggers the production of antibodies to destroy these red blood cells, resulting in a shortage of red blood cells in the circulation.
AIHA can either develop without an obvious underlying cause (primary AIHA), or secondary to another condition. These potential underlying conditions include viral infections (e.g., EBV, HIV, CMV, etc.), another auto-immune disease (e.g., lupus, rheumatoid arthritis, etc.), or the use of certain medication (e.g., antibiotics, certain anticancer drugs, etc.).
Depending on the type of antibodies that cause the disease, AIHA can be classified as warm or cold. Warm AIHA is the most common subtype and involves immunoglobin (Ig) G antibodies that bind to red blood cells at normal body temperature. Cold AIHA accounts for 10-20% of the AIHA cases and involves IgM antibodies. These antibodies can bind to red blood cells under cooler circumstances (i.e., cooler than the core body temperature).
While AIHA can theoretically affect people of all ages, it is most common in females over the age of 40.
Symptoms
Most of the AIHA symptoms are similar to what is seen with other forms of anemia. This includes weakness, chills, a fast heartbeat, pale skin, a yellowish coloring of the skin and whites of the eyes (jaundice), shortness of breath, chest pain and darkened urine. In addition to this, swelling of the spleen can lead to a feeling of fullness in the abdomen.
Specifically in patients with cold AIHA, symptoms may also include cold hands and feet, headaches, digestive problems, pain in the back and legs and a blue or red coloring of hands and feet.
Diagnostic tests
The diagnosis for AIHA usually starts with a set of blood tests to assess the number and shape of the different blood cells and to measure the hematocrit level. When these initial tests indicate anemia, additional blood tests will be performed. This includes a peripheral blood smear to look for red blood cell destruction and a reticulocyte count to evaluate the number of young red blood cells in the circulation. Other tests will evaluate the level of hemoglobin, lactate dehydrogenase (LDH) and haptoglobin in the blood as these measures may also be indicative for red blood cell destruction
In addition, a Coombs’ test is done to determine whether the body is making antibodies against red blood cells. if a cold AIHA is suspected, a blood sample is sent to the lab on ice an a cold agglutinin test will be performed to assess the level of antibodies that attack red blood cells at cold temperatures.
Treatments
While mild cases of AIHA often resolve on their own, more severe cases do require a specific treatment. In this respect, the first step in the treatment process is to address the underlying condition that causes the AIHA. For example, if the AIHA is linked to lupus, physicians will first try to get the lupus under control.
Additional therapies for AIHA mainly aim at silencing the immune system. In patients with warm AIHA this consists of corticosteroids and rituximab or other immunosuppressants. If these agents don’t work, such as in inherited forms of AIHA, the spleen can be surgically removed (splenectomy). The reason for this is that the spleen is the organ where most of the red blood cell destruction is taking place.
In contrast, the efficacy of corticosteroids and splenectomy in patients with cold AIHA is limited. For patients with mild cold AIHA, keeping warm by using hand/feet warmers, gloves, socks or even moving to a warmer climate may be enough to keep the disease under control. However, when this isn’t helping, medical treatment is needed. For these patients, the current standard first-line treatment consists of the monoclonal antibody rituximab with or without other immunosuppressive agents.
Want to submit input to improve quality content on this blood disorder?