Content
◉ Introduction
Autoimmune Hemolytic Anemia, as the name suggests, is an autoimmune disease where a faulty immune system causes the body to produce antibodies that attack and destroy red blood cells. This leads to a reduction in the number of red blood cells, which is known as anemia.
Autoimmune hemolytic anemia can develop as a result of an underlying disease, called secondary autoimmune hemolytic anemia, or without any previous viral illness or chronic condition, known as primary autoimmune hemolytic anemia.
The two main types of autoimmune hemolytic anemia are classified as warm and cold based on the antibodies involved, and each produces slightly different symptoms and signs. However, generally, the treatment of both types is similar.
◉ Warm Autoimmune Hemolytic Anemia
This occurs when the immune reaction happens at a temperature above 37 degrees Celsius (roughly the normal body temperature). It involves Immunoglobulin G antibodies, which are of limited specificity, and the symptoms generally show over the course of a few weeks.
Hemolysis mainly occurs intravascularly, and rarely in the liver and spleen. It does not occur as a result of direct lysis (destruction) of red blood cells.
◉ Cold Autoimmune Hemolytic Anemia
This type is also referred to as cold agglutinin or antibody disease, and it is the type where the antibodies react at a temperature lower than 37 degrees Celsius, such as when the body is exposed to cold. Usually, it occurs due to an idiopathic cause, or more prominently infections like Mycoplasma pneumoniae or infectious mononucleosis, or less frequently lymphoproliferative disorders.
The antibodies involved in the cold agglutinin type are usually Immunoglobulin M, and the hemolysis occurs in the extravascular system in the liver and spleen.
◉ Symptoms and Signs of Autoimmune Hemolytic Anemia
Symptoms of autoimmune hemolytic anemia slightly vary according to whether it is the warm or the cold type, but they show a wide range of symptoms such as:
- Fever
- Tiredness and exhaustion
- Muscle pain and weakness
- Palpitations and rapid pulse (increased heart rate)
- Shortness of breath and easy fatigability
- Pallor of skin
- Headaches and difficulty concentrating
- Jaundice (yellowish skin discoloration due to high bilirubin levels)
- Dark urine
- Diarrhea
- Chest pain
- Sense of abdominal fullness due to enlarged spleen
Symptoms specific to warm autoimmune hemolytic anemia tend to be as a result of the anemia and are less specific, but cold agglutinin disease may show additional symptoms that are mainly cold-associated but may also include:
- Heart murmurs
- Arrhythmias
- Heart failure
- Cold extremities
- Raynaud's disease
- Bluish discoloration in hands and feet
- Back and leg pain
- Vomiting, diarrhea, and other severe digestive issues
◉ Causes of Autoimmune Hemolytic Diseases
The most common cause of the majority of cases of AIHA is idiopathic, meaning the cause is unknown, and there is no underlying chronic disease or infection that might cause a secondary manifestation of this disease. However, these chronic diseases might include:
- Autoimmune diseases such as systemic lupus erythematosus, Sjogren's syndrome, thyroid disease, ulcerative colitis, and rheumatoid arthritis
- Cancers and myeloproliferative disorders including chronic lymphocytic leukemia and non-Hodgkin's lymphoma
- Infections such as Mycoplasma pneumoniae
- Viruses like Epstein Barr virus, mumps, HIV, rubella, and cytomegalovirus
- Some medications like penicillin, quinine, sulfonamides, and methyldopa
◉ Diagnosis of Autoimmune Hemolytic Anemia
For proper diagnosis of AIHA, your healthcare provider might request a Complete Blood Count (CBC) to see if anemia is present, which will alert the physician that hemolysis might be the cause of anemia.
Once anemia is diagnosed, mainly through low hemoglobin and red blood cell count, further investigations and tests are required. These might include:
- Reticulocyte count: raised reticulocyte count suggests the quick turnover and production of red blood cells indicating extravascular hemolysis. Extremely high reticulocyte count may also increase the MCV (mean corpuscular volume) value.
- Coombs test also known as direct antiglobulin test where a sample from the patient's blood is added to antiglobulin serum. Agglutination indicates that immunoglobulin or complement C is bound to the red blood cells. In warm AIHA type, immunoglobulin G is nearly always present, while immunoglobulin M is in the cold type.
- Cold agglutinin titer: this test is performed when cold autoimmune hemolytic anemia is suspected. It shows the amount of antibodies that attack the red blood cells at cold temperatures.
- Peripheral smear: examination of a blood sample under the microscope to see destroyed red blood cells. Schistocytes are helmet-shaped cells that are present when hemolysis occurs.
- Bilirubin test: bilirubin levels are increased as the red blood cells are destroyed, so high levels suggest hemolysis.
- Lactate dehydrogenase (LDH) level: LDH levels increase when red blood cells are destroyed as well since it is an enzyme that is present in their cytoplasm.
- Haptoglobin test: low levels of haptoglobin mean that it is being used up to remove red blood cell debris as they are being damaged by hemolysis.
◉ Treatment of Autoimmune Hemolytic Anemia
Autoimmune hemolytic anemia treatment is approached through the treatment of the underlying cause at first. So, upon management and treatment of lupus, for example, these symptoms should disappear. If medications such as sulfonamide are the cause, it is best if this medication is discontinued. Sometimes the symptoms are so mild no treatment is required.
The main line of medical treatment is a steroid prescription typically since it is an autoimmune disease, such as hydrocortisone, to reduce the immune system's ability to produce the antibodies that attack and destroy the red blood cells.
If steroids don't work, then immunosuppressants may be prescribed to stop the immune response and spare the bone marrow from being attacked. Sometimes medications don't work or don't produce a satisfactory result. When this happens, your healthcare provider might suggest surgery to remove the spleen (splenectomy). This is because the spleen is responsible for the elimination of abnormal cells floating around in the blood, so less destruction of red blood cells occurs when it is removed. Severe cases of autoimmune hemolytic anemia, warm or cold, may need regular blood transfusion to reduce the symptoms and prolong life expectancy.
◉ Conclusion
Autoimmune hemolytic anemia is a rare disease where the body mistakenly produces antibodies that attack and destroy the red blood cells causing symptoms of anemia and hemolysis. It has two types: cold and warm, classified according the temperature at which the immune reaction occurs. This typically occurs on top an already present chronic illness. Furthermore, it is diagnosed by a positive Coomb’s test and the first line of treatment is steroids.