ACQUIRED HEMOLYTIC ANEMIA
Hemolytic anemia is a condition in which there is destruction of RBC or removal of red blood cells from the circulation before their normal life span of 120 days. Many diseases, conditions, and factors can cause the body to destroy its red blood cells. These causes can be inherited or acquired. "Inherited" means hemolytic anemia occurs due to mutated gene passed from parents to offspring’s. "Acquired" means the person is not born with hemolytic anemia, but condition develops later due to failure of his/her own immune system. This happens because the immune system mistakenly recognizes these blood cells as foreign.
With acquired hemolytic anemias, red blood cells may be normal. However, some other disease or factor causes the body to destroy red blood cells and remove them from the bloodstream. The destruction of the red blood cells occurs in the bloodstream or, more commonly, in the spleen. Acquired hemolytic anemia can be divided into:
1. Immune Hemolytic Anemia
2. Non- Immune Hemolytic Anemia
Types of Acquired Hemolytic Anemia
1. Immune Hemolytic Anemia: In immune hemolytic anemia, immune system destroys red blood cells.
The three main types of immune hemolytic anemia are:
(i) Autoimmune hemolytic anemia (AIHA),
(ii) Alloimmune hemolytic anemia,
(iii) Drug-induced hemolytic anemia.
(i) Autoimmune hemolytic anemia (AIHA): In this condition, immune system makes antibodies (proteins) that attack red blood cells. AIHA accounts for half of all cases of hemolytic anemia. In some types of AIHA, the antibodies made by the body are called warm antibodies. These are active at warm temperatures and destroy red blood cells. In other types of AIHA, the body makes cold- reactive antibodies. These antibodies are active at cold temperatures. Cold-reactive antibodies can become active when parts of the body, such as the hands or feet, are exposed to temperatures lower than 32 to 50o Fahrenheit (0 to 10o Celsius).Warm antibody AIHA is more common than cold antibody AIHA.
(ii) Alloimmune hemolytic anemia:
This type of hemolytic anemia occurs if body makes antibodies against red blood cells that get from a blood transfusion. This occurs due to wrong blood transfusion. This type of hemolytic anemia also can occur during pregnancy if a woman has Rh- negative blood and her baby has Rh- positive blood.
(iii) Drug-induced hemolytic anemia: Certain medication alter normal function of immune system, In these cases, the immune system to mistakenly think the body's own red blood cells are dangerous, foreign substances. Antibodies then develop against the red blood cells. The antibodies attach to red blood cells and cause them to break down too early.
2. Non-Immune Hemolytic Anemia: Non-immune hemolytic anemia associated with high reticulocyte count, slight or marked increase of lactate dehydrogenase (LDH), increase of indirect bilirubin, increase of free Hb in plasma with almost no detection of haptoglobin and negative antihuman immunoglobulin (Coombs) test.
Causes
• Infections.
• Transfusion of blood from a donor with a blood type that does not match.
• Certain cancers.
• When antibodies form against red blood cells for no reason, the condition is called idiopathic autoimmune hemolytic anemia.
• Past blood transfusions
Symptoms
The symptoms acquired in hemolytic anemia are mild. If the problem develops slowly, symptoms that may occur first include:
• Feeling weak or tired more often than usual, or with exercise.
• Problems concentrating or thinking.
Diagnosis
• Absolute reticulocyte count.
• Direct or indirect Coombs test.
• Hemoglobin in the urine.
• LDH(level of this enzyme rises as a result of tissue damage).
• Red blood cell count (RBC), hemoglobin, and hematocrit.
• Serum bilirubin level.
• Serum free hemoglobin.
• Serum haptoglobin.
• Donath-Landsteiner test.
Treatment
The first treatment tried is most often a steroid medicine, such as prednisone. If steroid medicines do not improve the condition, treatment with intravenous immunoglobulin (IVIG) or removal of the spleen (splenectomy) may be considered. If the immune system do not respond to steroids. Drugs such as azathioprine (Imuran), cyclophosphamide (Cytoxan), and rituximab (Rituxan) have been used. Blood transfusions are given with caution, because the blood may not be compatible and it may cause more red blood cell destruction.
Prevention
Screening for antibodies in donated blood and in the recipient may prevent hemolytic anemia related to blood transfusions.