Current concerns in haematology 1: is the painful crisis of sickle cell disease a "steal" syndrome?

Article Abstract:

Although sickle cell anemia is a common condition that has received much attention, the recurrent attacks of pain associated with this disease are still not fully understood. Sickle cell disease is a hereditary condition in which defective crescent-shaped red blood cells are formed from a type of abnormal hemoglobin known as hemoglobin S. This condition primarily affects people of Mediterranean and African descent. The pain felt during sickle cell crisis may be concentrated in the abdomen or, more commonly, in the bone. The precise mechanism that causes these crises is unknown, but it has traditionally been thought to be associated with vaso-occlusive action, or blockage of blood vessels by the abnormal cells. However, some observed features of the disease do not support the vaso-occlusive concept to explain the pain crisis. Factors which precipitate these crises, as reported in a survey of sickle cell patients, are skin cooling, exercise, infection, and psychological stress. The pain is often reported to be distributed bilaterally and symmetrically; for example, both joints of the ankles will be affected at the same time. Higher concentrations of fetal hemoglobin, specific genotypes, and cyanate treatments are all associated with less severe sickling. Although these are known factors that inhibit the sickling process, they seem to have no significant effect on reducing the painful crises. It is proposed that centrally mediated reflexes, triggered by skin cooling, cause the shunting of the blood away from the bone marrow (where blood cells are manufactured), which may account for the symmetrical and bilateral distribution of the pain. This effect would remain independent of the factors that influence intravascular sickling. This process, described in a hypothesis referred to as a 'steal syndrome', is more consistent with the symptoms observed during the pain episodes than the vaso-occlusive theory. New methods for preventing and treating the painful crises associated with sickle cell anemia may be discovered through the further exploration of this hypothesis. (Consumer Summary produced by Reliance Medical Information, Inc.)

Complications and side effects, Physiological aspects

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Current problems in haematology 2: hereditary spherocytosis

Article Abstract:

Hemolytic anemia is a condition characterized by the destruction of red blood cells. Spherocytosis is the most common form of inherited hemolytic anemia, and is caused by a defect in the red blood cell membrane that makes the cell very fragile, causing it to rupture. clinical findings are spleen enlargement (splenomegaly), gall stone formation, a deficiency of folic acid, and increased susceptibility to viral infection. Spherocytosis is estimated to occur in 1 out of every 5,000 births. In most cases, the disease begins as a mild-to-moderate form of anemia during childhood. There is no single test that can be used to diagnose this disease. However, the combined use of several different types of blood tests can establish an accurate diagnosis. These tests measure the number of red blood cells, their fragility, and how easily and quickly they rupture. The severity of the disease can be estimated by measuring the amount of a specific protein called spectrin, which is found in red blood cell membranes. This protein gives the membrane its strength, and a deficiency of spectrin causes the membrane to become fragile. Therefore, the lower the amount of spectrin, the more severe the disease. In the most severe cases of spherocytosis, surgery is performed to remove the spleen (splenectomy). However, sepsis (pus-forming bacteria in the blood) is a common complication following splenectomy. The sepsis can be minimized using benzyl penicillin and a vaccine. Ultrasound imaging should be performed before splenectomy to determine if the patient has gallstones. If gallstones are present, the gall bladder should be removed at the same time as the spleen. (Consumer Summary produced by Reliance Medical Information, Inc.)

Abnormalities, Diagnosis, Hemolytic anemia, Spherocytosis, Hereditary, Hereditary spherocytosis

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Patterns of mortality in sickle cell disease in the United Kingdom

Article Abstract:

Sickle cell disease is a disease that causes red blood cells to become deformed. The red blood cells of patients with sickle cell disease are crescent or sickle-shaped instead of their normal circular shape and do not function properly. In a previous survey conducted in the UK, 37 deaths out of 1,367 cases of sickle cell disease were reported; 25 of the deaths occurred in children under the age of 16, and 14 of these deaths were sudden. In a study conducted in North America, 49 out of 422 patients with sickle cell disease died before they reached the age of 10. Lung infections were one of the most common causes of death in these patients. The National Cooperative Study of Sickle Cell Disease in the US predicted that 89 percent of the patients with sickle cell disease will survive to the age of 20. The majority of the deaths reported in this study were caused by infections and occurred within the first three years of life. To determine the incidence of and factors associated with mortality from sickle cell disease in the UK, the medical records of 384 patients with sickle cell disease, who were listed in the Brent sickle cell disease register, were reviewed. Between 1974 and 1989, 18 (5 percent) of the patients died. Five of the patients were less 16 years of age at the time of death. Twelve of the 18 deaths were caused by lung problems, and 10 of the deaths occurred suddenly. It is concluded that early diagnosis of the disease and identifying the causes of death that can be prevented, such as lung infection, are the most likely methods of reducing mortality from sickle cell disease. (Consumer Summary produced by Reliance Medical Information, Inc.)

Reports, Patient outcomes, Mortality, Genetic disorders, Epidemiological research, Cross sectional studies

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