Autoimmune Hemolytic Anemia (AIHA) is a blood disorder that occurs when the body's immune system mistakes red blood cells as threats and produces antibodies to destroy them. Red blood cells are responsible for transporting oxygen throughout the body. When antibodies destroy red blood cells faster than the body can replace them, body tissues may not receive enough oxygen, which can lead to symptoms such as fatigue, weakness, and headaches.
AIHA is rare, affecting 1 to 3 people per 100,000 each year. The exact cause of AIHA is currently unknown, but sometimes infections, medications, or an underlying autoimmune disease can cause this condition. Treatment for AIHA typically involves medication to suppress the immune system and, if AIHA symptoms are severe, blood transfusions to replace lost red blood cells.
There are two types of autoimmune hemolytic anemia (AIHA), which healthcare providers classify based on the temperature at which the immune system attacks red blood cells. This distinction is important because each type of AIHA requires a different treatment approach.
Warm autoimmune hemolytic anemia
Warm autoimmune hemolytic anemia (w-AIHA) is the more common type, accounting for approximately 70% to 80% of adult AIHA cases and 50% of pediatric AIHA cases. In this type, immune system antibodies that attach to and attack red blood cells become activated at normal body temperature, causing anemia.
Cold Autoimmune Hemolytic Anemia
cold autoimmune hemolytic anemia (c-AIHA) or cold agglutinin Disease (CAD) most commonly affects adults between the ages of 40 and 80. In CAD, antibodies are activated at lower temperatures, attach to red blood cells, and are destroyed. When exposed to cold temperatures, the antibodies become activated, causing the red blood cells to clump together and be destroyed.
Primary and secondary autoimmune hemolytic anemia
Healthcare providers sometimes classify AIHA based on the underlying cause of the condition.
- 1st AIHA: About 50% of AIHA cases are primary or idiopathic, meaning there is no identifiable underlying cause.
- 2nd AIHA: Secondary AIHA occurs in response to an underlying condition, such as an autoimmune disease, cancer, infection, or certain medications.
Symptoms of autoimmune hemolytic anemia vary depending on the severity of the condition. Red blood cells contain hemoglobin, a protein that helps carry oxygen to body tissues. Hemolytic anemia occurs when the body does not have enough red blood cells to deliver oxygen-rich blood to the tissues.
Symptoms of AIHA tend to develop gradually and may include:
If your body loses red blood cells faster than it can replace them, your symptoms may get worse and you may develop new symptoms, including:
If severe AIHA is left untreated, problems such as:
Without AIHA, the immune system protects against foreign invaders (e.g. bacteria, viruses) that could cause infection. However, with AIHA, the immune system incorrectly identifies healthy red blood cells as a threat and produces antibodies to destroy them.
Normally, red blood cells survive for about 120 days before the spleen filters them out and removes them from the bloodstream. With AIHA, antibodies destroy red blood cells prematurely (before their time) and faster than the body can replace them, causing a shortage of red blood cells in the body.
It is not known what causes this abnormal immune response in primary AIHA. However, several factors may trigger the development of secondary AIHA, including:
- infection: Viral and bacterial infections, including influenza (flu), certain types of pneumonia, tuberculosis, and Epstein-Barr virus (EBV).
- drug: Certain drugs, such as nonsteroidal anti-inflammatory drugs (NSAIDs), chemotherapy drugs, antivirals, and antibiotics, can stimulate the production of antibodies that destroy red blood cells.
- Autoimmune diseases: Systemic lupus erythematosus (lupus), Sjogren's syndrome (SS), systemic sclerosis (SSc), and rheumatoid arthritis (RA)
- Immunodeficiency (weakened immune system): Bone marrow or organ transplants can affect immune system health.
- Specific cancers: Lymphoma, chronic lymphocytic leukemia, ovarian cancer and prostate cancer.
Risk factors
Anyone can develop AIHA, but certain risk factors may increase your chance of developing AIHA. These risk factors include:
- age: AIHA is most common in older adults between the ages of 50 and 80.
- sex: This blood disorder is more common in people who were assigned female at birth.
- Underlying health conditions: Living with an autoimmune disease, blood cancer, or a weakened immune system may increase your risk of AIHA.
To diagnose autoimmune hemolytic anemia, your healthcare provider will review your medical history, ask questions about your symptoms, and perform a physical examination. The doctor also orders a series of diagnostic blood tests to evaluate red blood cell (RBC) health, check for the presence of hemolytic (RBC-destroying) antibodies, and rule out other possible causes of anemia.
Blood tests to diagnose AIHA include:
- Complete Blood Count (CBC): It measures the levels of various blood cells in the blood, including red blood cells, white blood cells, platelets, and hemoglobin.
- reticulocytes count: The number of young red blood cells (called reticulocytes) in the blood is evaluated to determine whether the bone marrow is replacing lost red blood cells quickly enough.
- Peripheral blood smear: It involves examining the shape and size of red blood cells under a microscope to identify abnormal cells. Spherical red blood cells may help confirm the diagnosis of autoimmune hemolytic anemia.
- Coombs Test: Diagnosis of autoimmune hemolytic anemia is confirmed by detecting the presence of red blood cell destroying antibodies attached to red blood cells or in the bloodstream.
- Lactate dehydrogenase (LDH) test: Check the level of LDH, an enzyme released when red blood cells are broken down.
- Haptoglobin test: It tests the level of haptoglobin in the blood, which decreases when red blood cells are broken down or antibodies destroy them prematurely.
- Bilirubin test: Tests levels of bilirubin, a byproduct of the breakdown of red blood cells in the body, which may be increased due to hemolytic anemia.
- Agglutinin test: To help diagnose AIHA, they look for the presence of agglutinins, antibodies that cause red blood cells to clump together.
If you are diagnosed with autoimmune hemolytic anemia, the main goal of treatment is to reduce anemia symptoms by inhibiting the immune system from attacking red blood cells. Treatment depends on the severity of the condition and the type of AIHA (warm or cold).
drug
Corticosteroid medications, such as Rayos (prednisone), are the first-line treatment for managing AIHA. This medication helps slow or stop the premature destruction of red blood cells by suppressing abnormal immune responses. Up to 80% of people with AIHA experience improvement in symptoms within 2 to 3 weeks with corticosteroid treatment.
If your symptoms do not improve within 3 weeks, your healthcare provider may prescribe Rituxan (rituximab), a monoclonal antibody that helps relieve AIHA symptoms.
Splenectomy
If medications don't work or you have severe warm AIHA, your health care provider may recommend splenectomy (surgical removal of the spleen). The spleen filters blood cells and is often the primary site of red blood cell destruction in AIHA. Removal of the spleen relieves symptoms in up to 90% of patients with mild AIHA who undergo surgery.
Blood transfusion
If you have severe AIHA, your doctor may recommend a blood transfusion to replenish your body’s supply of red blood cells and improve oxygen delivery to your body’s tissues. Some people with severe AIHA require frequent blood transfusions to help manage their symptoms.
Lifestyle adjustments
Your healthcare provider may recommend other suggestions to help you stay comfortable, such as:
- Avoid cold temperatures: If you have AIHA, your doctor may recommend that you avoid exposure to cold temperatures or swimming in cold water to prevent the onset of symptoms. If you live in a naturally cold climate, it may be helpful to wear extra clothing to keep your body warm.
- Take folic acid supplements: Folic acid (also known as folate) supplements help support red blood cell production and lower the risk of serious anemia symptoms. Your healthcare provider will often recommend these supplements along with other medications you are taking.
Because there are so many potential triggers, it is not always possible to prevent autoimmune hemolytic anemia. However, if you are diagnosed with AIHA, there are steps you can take to reduce the frequency and severity of your symptoms.
- Basic Condition Management: If AIHA is associated with another condition, such as an autoimmune disease, following a treatment plan may help lower the risk of AIHA symptoms recurring (the period when symptoms are most active).
- Prevent infection: To reduce your risk of getting sick, practice good hygiene, keep your immunizations up to date, and avoid contact with people who are infected with bacteria or viruses.
- Minimize exposure to cold: If you have cold AIHA, avoiding cold environments and dressing warmly in cold weather can help prevent red blood cell destruction.
Autoimmune hemolytic anemia can cause complications, which may occur due to low red blood cell counts or in response to treatment. These complications include:
- Spleen size: If red blood cells are destroyed rapidly and the spleen becomes enlarged, abdominal pain may occur and the risk of spleen rupture may increase.
- infection: Taking immunosuppressants or having a splenectomy (surgery to remove the spleen) to treat AIHA may weaken your immune system and increase your risk of developing viral and bacterial infections.
- thrombosis: Abnormal destruction of red blood cells increases the risk of blood clots forming in veins or arteries (called thrombosis). These blood clots can reduce or block normal blood flow and increase the risk of a heart attack or pulmonary embolism (blood clots in the lungs).
- Skin ulcers: In cold AIHA, reduced blood flow after exposure to cold causes red blood cells to clump together, increasing the risk of skin ulcers or tissue necrosis (called necrosis) in the extremities, such as the fingers and toes.
- Kidney dysfunction: Breakdown products from destroyed red blood cells can overload the kidneys, potentially leading to kidney problems.
Autoimmune hemolytic anemia (AIHA) is a rare condition that causes the immune system to accidentally attack healthy red blood cells (RBCs). This can lead to anemia and cause symptoms such as fatigue, shortness of breath, and dizziness.
The exact cause of AIHA is not known, but certain infections, medications, and health conditions can trigger the development of AIHA. Treatments such as medications and procedures can help manage symptoms and improve quality of life.