Реферат: Sickle Cell Anemia 4 Essay Research Paper
Sickle Cell Anemia 4 Essay, Research Paper
There have been many researches and tests done on the genetic causes of Sickle Cell Anemia and how it developes, as well as it s effects on the circulatory, muscular, and respiratory systems, as well as it s effects on the joints and other systems of the body, and the complications associated with them. Most of the research has been done to explore on the reasons why it mostly effects the African-American community and people who are from the West Coast of Africa. It has also been known that Sickle Cell Anemia also effects people from the Mediterranean countries (Wethers, 2000)
Sickle Cell Anemia is a the most common single gene disorder found mostly among Black Americans (Wethers, 2000). According to scientific research, it affects approximately one in 375 persons of African ancestry. According to one researcher, Sickle Cell conditions are also found to be in persons from Mediterranean countries also, such as Turkey, the Arabian peninsula, and the Indian subcontinent ( Wethers, 2000, p.1014). Extensive research has also proved that Spanish speaking persons in the United States, plus people from the Caribbean and South and Central America, are also effected by Sickle Cell Anemia (Wethers, 2000)
The first case of Sickle Cell Anemia was first published in 1910 by scientists, and has since then been followed by at least six decades of many observations, which include genetic, molecular, and pathologic observations (Wethers, 2000) Large bodies of clinical data has on the evolution of Sickle Cell Anemia from birth has been gathered on studies of children since the 1970 s (Wethers, 2000) The United States has studied 3,500 patients
with the Sickle Cell disease, and based on these studies, the longevity and quality of life of these patients have greatly improved (Wethers, 2000). It has been researched and proven that Sickle Cell Anemia have come from mutations within the human genes that is associated with being immune to malaria, a parasitic blood disease which is carried and contracted by infected mosquitoes (Wethers, 2000) Since malaria is mostly found in hot, moist areas in West Africa and the Mediterranean, people originating from that area produced an immunity to towards malaria, but with consequences. The individual will not contract malaria because the mutation in his or her genes quickly fights off the disease by changing the shapes and composition make-up of the blood cell so the parasites will not be able to survive in it. (Wethers, 2000).
The consequence of this is that because the individual s blood cells mutates and becomes misshapen, becoming moon-crescent or sickle-shaped, or even get spiked shaped. The blood cells then grows and becomes too big to pass through most blood vessels, mostly capillaries and veins, and clump together, forming a mass. (Wethers, 2000) The blood vessels where this happens mostly is associated with the joints and the lungs. When this happens, the child or adults experiences great amounts of pain in their joints and fingers, making it almost impossible for them to ambulate. The joints then get swollen and red. Another condition is that the clump of mutated blood cells can travel to the vessels of the heart and cause a blockage. This is called a thrombosis (Wethers, 2000)
According to research, The most common forms, or variants of Sickle Cell Anemia are homozygous (hemoglobin SS disease), doubly heterozygous sickle cell
hemoglobin C disease (hemoglobin SC disease), and the sickle Beta-thalassemias (Wethers, 2000, p. 1014) Children and adults with homozygous sickle cell disease inherit a sickle cell (S) gene from each of their parents, and shows all the signs and symptoms of Sickle Cell Anemia, such as painful joints, chest pain, and kidney problems (Wethers, 2000). Individuals with hemoglobin C disease inherit the S gene from one parent and a C gene from another. This means that they also show all the signs and symptoms of Sickle Cell Anemia (Wethers, 2000) In studies, it was shown that no normal hemoglobin (hemoglobin A) are produced by either one of the patients who has anyone of the forms of the disease (Wethers, 2000)
With individuals born with sickle cell Beta-Thalassemias, the Beta [sup A] gene has mutated, and they are unable to produce the normal Beta [sup A] globin chain (Beta [sup b]) or a reduction in it s production (Beta [sup +]) (Wethers, 2000) This adult or child with Beta-Thalassemias inherited the S gene from one parent and the Beta-Thalassemia gene from the other. Like the others, this person will show the signs and symptoms of Sickle Cell Anemia. People with the Sickle Cell trait, which is the carrier form of this disease, will have more than 50 percent normal hemoglobin. They are asymptomatic (Wethers, 2000) Because Sickle Cell Anemia is genetic and inherited, most Blacks, Hispanics, and people of the Mediterranean are very careful about who they marry and have children with. Carriers or people with no history of Sickle Cell disease in their family history are preferred.
With new advances, the Sickle Cell disease can be diagnosed in newborns and older persons. Test mostly used are DNA (deoxynucleic acid) analysis, which tests the child and parent s phenotype or genetic make-up, and complete blood counts, with counts and tests to see if the amount of blood cells is normal or decreased. The normal blood count for a person would be in the range of 3.6. Anything below that point would be considered abnormal. (Wethers, 2000, p.1014)
There are many kinds of complications with Sickle Cell Anemia that can become very severe if left untreated. Some of these complications include infection, acute splenic sequestration crisis, renal complications, Acute Chest Syndrome, and pain (Wethers, 2000) With infection, individuals with Sickle Cell are susceptible to sepsis, which is caused by germs and bacteria. Blood cultures are important and should be obtained in anyone with high temperatures because it will test and count for the rise in the amount of White Blood Cells, (leukocytes) present within the blood. The high presence of leukocytes in the blood, at least over 28,000 per mm [sup 3] (28 3 10 [sup 6 per Liter) high sedimentation rate, usually means an infection in the body (Wethers, 2000, p 1309) According to another study, Therapy with cephalosporin, (eg., cefotaxime, [Claforan]), ceftriaxone [Recephin], or cefuroxime [Ceftin] is recommended for a child or adult with high fever. (Wethers, 2000, p. 1309) Antibiotics are largely used to treat infection.
Acute splenic sequestration crisis is large due to splenitis, which is the swelling of the spleen (Wethers, 2000) It is accompanied by the fall of hematocrit count and rise of the reticulocyte count. The spleen is enlarged because of trapped blood and it causes circulatory problems and compromises. This is mostly found in children less than three years of age with homozygous sickle cell disease (Wethers, 2000) The procedure done for this condition is a splenectomy, which is the removal of the spleen, when the child is strong enough to endure the surgical procedure.
Aplastic crisis is when the production of bone marrow in children or adults with sickle cell disease pauses (Wethers, 2000) It is caused by the Human parovirus B19 infection. It is usually self-limiting and causes mild symptoms, such as fatigue, or tiredness. If the blood hematocrit falls to low, then blood transfusion is recommended. It is for when the hematocrit falls at least 20-25% below baseline, which is 3.6 (Wethers, 2000)
According to studies done, It is shown that half of children and adults with Sickle Cell Anemia develop Acute Chest Syndrome. (Gladwin, T.; Rodgers, P., 2000, p.1476). Acute Chest Syndrome is a condition which consists of many signs that include pulmonary infiltrates on the chest radiograph, fever, cough, chest pain, dypsnoea, hypxaemia (mean PaO [sub 2] of 71 mmHg), and leucocytosis. (Gladwin, T.; Rodgers, P., 2000, p.1476). Others complications of this syndrome include pulmonary infection,
vascular obstruction, which is caused by sickling or clumping of the blood in the vessels, and macrovascular pulmonary embolism, or a blood clot in the lungs. (See Appendix 1) Studies show that most adults with Sickle Cell Anemia, this pulmonary disease occurs secondary to vaso-occlusive crisis that causes bone-marrow infarction and fat embolisation (Gladwin, T.; Rodgers, P., 2000)
Recent studies showed that treatments with nitrous oxide (NO) can be useful in controlling and treating Acute Chest Syndrome. Reports indicates that patients show improvements of oxygenation and reductions of pulmonary artery pressures during the inhalation of nitrous oxide. (Gladwin, T.; Rodgers, P., 2000) It has been approved by the United States Food and Drug Administration for use in treating this syndrome.
In renal complications, the kidneys are prone to damage from the sickle cells. Studies show that children with sickle cell disease and sickle cell trait cannot concentrate urine and are highly susceptible to enuresis, or the inability to urinate. Hematuria, or blood in the urine, can occur with all types of sickle cell disease. According to research The amount of blood is usually mild, but can become severe enough to warrant a blood transfusion if left untreated. (Wethers, 2000) Studies also indicate that any child with who has a gross blood amount in the urine should undergo genitourinary tests (Wethers, 2000) Studies show that in the second decade of life, children with sickle cell disease show high signs of chronic kidney damage.
Pain is shown by research to be the most distressing symptom on patients with Sickle Cell Anemia (Wethers, 2000) Pain can vary in degree from very mild to severe to debilitating, especially in children, and can interfere with school and employment (Wethers, 2000). Because sickle cell can be quite episodic and severe at times, the patient should be treated with narcotics (Wethers, 2000).
It is shown by research that the patient can develop a tolerance to the medication over time so they may require large doses of narcotics. Once the pain is gone, the medication should be discontinued (Wethers, 2000) The medications used for pain are Ibuprofen (Advil or Motrin) or acetaminophen (e.g., Tylenol) (Wethers, 2000). For more severe pain, morphine is preferred because morphine can be given subcutaneously if venous access in a problem (Wethers, 2000). Meperidine is not strongly used because it can cause seizures after a few days of use (Wethers, 2000).
Bone marrow transplant has also has a big impact on treating Sickle Cell Anemia. In a recent study done, 50 children received matched sibling marrow transplants in one of 24 transplant centers in United States and Europe from 1991-1999. The probability of survival for 8 years following transplant was 94%. Event free survival was 84% and estimated 10% incidence for graft rejection and return of sickle cell disease. (Lamp, 2000, Clinical Pediatrics, p.495). According to the studies, 22 patients of 26 who had a two year follow up were resolved of their sickle cell disease (Lamp, 2000). The first case of bone marrow transplant to treat Sickle Cell Anemia was in the United States in 1983 on an 8 year old girl with Sickle Cell Anemia and acute myelogenous leukemia, and she was cure of both diseases (Lamp, 2000).
In the treatment of Sickle Cell Anemia, there have been many ways to treat the complications that come with it. There have been many advances in treating pain, renal complications, Acute Chest Syndrome, and infections, and testing for Sickle Cell. Many of these treatments include blood cultures to test for high leukocytes, use of pain medications for pain, and tests shown to detect blood or protein in the blood. For the Acute Chest Syndrome, nitrous oxide is the best treatment. There are even DNA analysis testing to see who is likely to have children with Sickle Cell Anemia. Also, bone marrow transplant has proven very effective in treating and helping to cure sickle cell disease, although the experience with it has been limited (Lamp, 2000). According to studies, in another 20 years, Sickle Cell Anemia will become one of many chronic illnesses that if properly handled and treated, will not interfere with activity, growth, and mental development (Wethers, 2000).