This is often associated with an infection by Parvovirus B-19. The bone marrow's replacement of the cells is disrupted. This usually manifests with a rapid drop in hemoglobin levels. Luckily, this condition is usually self limited, and the treatment is mostly supportive. Recovery is usually heralded by an increase in the reticulocyte count.
In children and in adolescents, sickle cell disease causes growth retardation, a delay in the manifestation of secondary sexual characteristics and sexual maturation, and usually results in the child being significantly underweight. It often happens in childhood that the spleen enlarges, especially in the first year of life, resulting from the sequestration of a large number of sickled cells within the spleen. This is a painful process. The spleen will then have repeated infarcts, and splenic function is impaired during the enlargement. Eventually, the repeated episodes of infarct leave the spleen fibrotic and it shrinks in size, becoming non-functional. In effect, this is called an autosplenectomy. The lack of spleen means that the patient with sickle cell disease suffers from an immune deficiency, and is particularly sensitive to encapsulated organisms like Streptococcus pneumoniae. Pneumococcal infections are common during the childhood of patients with sickle cell disease, as are infections with gram negative organisms in adult life.
Infants with sickle cell disease may often suffer from dactylitis, which causes painful swelling in the dorsum of the hand and foot. This can result in cortical thinning in the bones, and is not usually associated with erythema. Another syndrome called acute chest syndrome is seen, is which the patient has chest pain, fever; rapid breathing and pulmonary infiltrates are seen on chest x-ray. Acute chest syndrome is considered a medical emergency; as if it is not treated quickly it may lead to acute respiratory distress syndrome and death. The central nervous system is not immune from the effects of sickle cell disease. The most prevalent manifestation of central nervous system involvement is embolic stroke, which may have varying degrees of neurological involvement. The cardiovascular system can also be affected, since the chronic and recurrent hemolysis may lead to hemosiderin deposition within the myocardium, which in turn leads to dilation of the ventricles and congestive heart failure. The patient with sickle cell disease may also suffer from gallbladder disease, repeated infarction of the joints and bones, pulmonary hypertension from repeated micro infarction, renal failure secondary to loss of concentrating ability.
The patient may lose vision due to retinal vascular infarcts. Leg ulcers are also a common painful issue, and because of the poor circulation associated with this disease, healing is poor and infection common.
Adult females who become pregnant and who have sickle cell disease are also at high risk. For these women there is a very high rate of miscarriage. Placenta previa and abruption are common due to hypoxia and infarction. The babies born to sickle cell disease mothers are often premature and have a low birth weight due to incompetent placental function.
Treatment options for Sickle Cell Disease
Because so much is known about the genetics and pathophysiology of sickle cell disease, the causes of the physical manifestations are well understood. None the less, there is no cure. In managing the patient with sickle cell disease, the goal is to avoid crises when possible, and manage symptoms as they occur. The vasoocclusive crisis is treated with vigorous hydration and analgesics. Patients are usually given intravenous fluids in sufficient amount to correct any dehydration. This is usually best managed on an inpatient basis. Pain management usually requires the use of opiates. Morphine continues to be the drug of choice in the acute crisis, while non-steroidal anti-inflammatory drugs like ibuprofen can be used for the chronic and bone pain. It may also be helpful to use certain drugs like tricyclic antidepressants, which tend to have a synergistic effect with pain management and may reduce the need for opiates. Vigorous attention to prevention of infection is also important. Every patient with sickle cell disease should receive the pneumococcal vaccine at age 2 with a booster shot at age 5 to reduce incidence of pneumococcal infection. Some children are even placed on prophylaxis with penicillin during infancy, until such time as they can receive the vaccine. Adult patients are best treated with broad spectrum antibiotics empirically until therapy can be tailored to the causative organism by culture and sensitivity. There is some thought that allogenic bone marrow transplantation can cure this disease, but there are so many risks associated, and so few matched donors, that this does not, in most cases, represent a feasible plan.
While several drugs have been tried for the treatment of sickle cell disease, the only drug which is currently approved by the FDA for the treatment of sickle cell disease is hydroxyurea, which increases the production of hemoglobin F, thereby retarding sickling This medication can decrease the frequency and severity of vasoocculsive crises, reduce chronic pain and lead to a better quality of life. Unfortunately, hydroxyurea is a potentially carcinogenic medication, and its long-term effects have yet to be seen. Patients who currently use hydroxyurea must have frequent blood tests with careful attention for the presence of luekopenia and thrombocytopenia. In order to qualify for this drug, the patient must have at least 6 painful crises in a year, severe chronic pain which is unresponsive to conventional methods of control, acute chest syndrome or a history of stroke.
The patient's mental well being, in light of this chronic and potentially disabling disease must also be considered. The patient may benefit from referrals to pain management experts, social workers, psychiatrists and physical therapists, substance abuse counselors, and vocational rehabilitation workers.
Patients who suffer from sickle cell disease have a chronic, disabling and potentially life threatening disease which manifests almost from the time of birth. This disease may be one of the most studied, and possible one of the most well understood on a pathophysiological basis, but still no cure exists. Patients require comprehensive care and careful attention to prevention of crises.
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