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Encyclopedia -> Disease -> S -> Sickle cell anemia Alternate Names: Anemia - sickle cell; Hemoglobin SS disease (Hb SS); Sickle cell disease Causes and Risks: Sickle cell anemia is caused by an abnormal type of hemoglobin (oxygen carrying pigment) called hemoglobin S. It is inherited as an autosomal recessive trait; that is, it occurs in someone who has inherited hemoglobin S from both parents. Someone who inherits hemoglobin S from one parent and normal hemoglobin (A) from the other parent will have sickle cell trait. Someone who inherits hemoglobin S from one parent and another type of abnormal hemoglobin from the other parent will have another form of sickle cell disease such as sickle cell-b 0 thalassemia, hemoglobin SC disease, or sickle cell-b + thalassemia. Someone with sickle cell trait or these forms of sickle cell disease will usually have no symptoms or only mild ones. However, some of these conditions can cause symptoms similar to sickle cell anemia. The overall incidence is eight out of 100,000 people. However, it is more common in some populations, affecting one out of 600 African Americans and one out of 1,000 to 1,400 Hispanic Americans. Because people with sickle trait were more likely to survive malaria outbreaks in Africa than those with normal hemoglobin, it is believed that genetically aberrant hemoglobin evolved as a protection against malaria. Although this disease is inherited and present at birth, symptoms usually don’t occur until after 4 months of age. Sickle cell anemia may become life threatening when damaged red blood cell break down (hemolytic crisis) or bone marrow fails to produce blood cells (aplastic crises). Repeated crises can cause damage to the kidneys, lungs, bone, liver (incidence less than two percent), and central nervous system. Blocked blood vessels and damaged organs can cause acute painful episodes. These painful crises, which occur in 70% of patients, can last hours to days, affecting the bones of the back, the long bones, and the chest. Some patients have one episode every few years, while others have many episodes per year. The crises can be severe enough to require admission to the hospital for pain control and intravenous fluids. Many manifestations of this disease are a result of the fragility and inflexibility of the sickle red blood cells. When patients experience dehydration, infection, and low oxygen supply, these fragile red blood cells assume a crescent shape, causing red blood cell destruction and thickening of the blood. Prevention: Sickle cell anemia can only result when two carriers with sickle cell trait have a child together. Therefore, genetic counseling is recommended for all carriers of sickle cell trait (about 1 in 12 African Americans has sickle cell trait). Prenatal diagnosis of sickle cell anemia is also available. Prompt treatment of infections, adequate oxygenation, and preventing dehydration may prevent sickling of red blood cells. Antibiotics and vaccinations may prevent infections. General health visits with a physician are recommended to ensure the patients is getting adequate nutrition, maintaining proper activity levels, and receiving proper vaccinations. In incentive spirometry, the patient breathes into a plastic tube that has a ball inside. By trying to breathe hard enough to force the ball up the tube, the patient receives more oxygen. Using this treatment when chest pains begin may decrease the complications of acute chest syndrome. Prenatal diagnosis is now possible for couples at risk of producing a child with sickle cell anemia. Symptoms:
Additional symptoms that may be associated with this disease:
Signs and Tests: Common signs include:
Tests commonly performed to diagnose and monitor patients with sickle cell anemia include:
Patients with sickle cell may have abnormal results on certain tests, as follows:
Treatment: There is currently no known cure for the disease. Therefore, the purpose of therapy is to manage and control symptoms resulting from crises. During a crisis, bed rest is recommended to reduce energy expenditure and oxygen needs. Maintaining adequate oxygen levels prevents the acidosis, which can cause sickling. Supplementation with Folic acid, an essential element in producing cells, is required because of the rapid red blood cell turnover. Acute painful episodes are treated with analgesics and adequate liquid intake. Sometimes the spleen become damaged from these aberrant red blood cells and must be removed (splenectomy). Blood transfusions may be given for aplastic or hemolytic crises, but should not be given routinely. Patients who have had a splenectomy are given a pneumococcal vaccine to prevent overwhelming infection. Since this vaccine is not very effective in children, children with splenectomies receive penicillin to prevent infection until they are old enough for the vaccine to be effective. Oral or intravenous fluids are given to dilute the blood and replace lost electrolytes. Blood transfusions are given for symptomatic or severe anemia, low oxygen (hypoxia) accompanying acute chest syndrome, and to prevent recurrent strokes. It is possible for patients to become addicted to the narcotics used to treat painful episodes. However, patients with sickle cell are not more likely to become addicted than other patients taking analgesics for common pain. Nevertheless, this remains a real concern. There are specific treatments available for the complications of sickle cell anemia. These include antibiotics for infection; partial exchange transfusion (and, rarely, intubation or even extracorporeal membrane oxygenation —ECMO—) for acute chest syndrome; potentially partial exchange transfusions or surgery for neurological events such as strokes; dialysis or kidney transplant for kidney disease; irrigation or surgery for priapism; surgery for eye problems; hip replacement for avascular necrosis of the hip (death of the joint); gallbladder removal if there is significant gallstone disease; wound care, zinc oxide or surgery for leg ulcers; drug rehabilitation and counseling for the psychosocial complications. Hydroxyurea (Hydrea) was found to help some patients to produce a more normal blood protein reducing the frequency of painful crises and of acute chest syndrome, and reducing the need for blood transfusions. However, it may cause leukemia if used for extended periods of time. Therefore, is recommended only for those patients at great risk for complications of the disease. Newer drugs are being developed to manage sickle cell anemia. Drugs such as clotrimazole may help prevent dehydration, which can cause sickling. One drug now being tested improves the shape of sickled cells so they can move through blood vessels more easily. Vasodilators (drugs which dilate blood vessels) such as nitric oxide (NO) may also keep blood vessels from becoming blocked, improving acute chest syndrome. Antioxidants may also help, but their role is not well understood. About 1% of the hemoglobin produced in the human body is fetal hemoglobin (Hb F). Even people with sickle cell anemia produce normal Hb F. Drugs such as butyric acid, which cause the body to produce more Hb F than normal, can therefore help treat sickle cell anemia. Bone marrow transplants are currently the only potential cure for sickle cell anemia. However, it is difficult to find the right bone marrow donor, and the drugs needed to make the transplant possible are highly toxic. Also, bone marrow transplants are much more expensive than other treatments. Gene therapy may be the ideal treatment, but it has not yet been tested in humans. Parents whose children have sickle cell should encourage their children to lead normal lives. However, in order to decrease the occurrence of sickle cell crises, consider the following precautions: A. To prevent tissue deoxygenation, avoid the following:
B. To promote proper hydration:
C. To avoid sources of infection:
Support Groups: Sickle cell anemia, like other chronic, life-threatening diseases, can cause great stress to the patient and family members. Joining a support group, where members share common experiences and problems, can relieve this stress. See sickle cell anemia - support group. Prognosis: In the past, death from organ failure occurred between the ages of 20 and 40. More recently, because of better understanding and management of the disease, patients live into their forties and fifties. Causes of death include organ failure and infection. Some people with the disease experience minor, brief, and infrequent episodes. Others experience severe, prolonged and frequent episodes resulting in many complications. Complications:
Call your health care provider if acute painful crises occur or at the first sign of any infection.
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