Sickle cell anemia
Last reviewed: 23.04.2024
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Sickle cell anemia is a severe chronic hemolytic anemia that occurs in persons homozygous for the sickle-shaped gene, accompanied by a high mortality rate. Most often, this disease occurs in people from Africa. The incidence of sickle cell anemia is 1: 625 newborns. Homozygotes do not synthesize HbA, their erythrocytes contain 90-100% HbS.
Sickle-cell hemoglobinopathies are widespread among people living in tropical Africa and in some areas of India, less common in the Mediterranean, the Middle East, and the Americas. In connection with the widespread migration of the population recently began to occur in Western Europe.
Sickle-cell anemia is caused by homozygosity in Hb S or double heterozygosity: Hb S-β-thalassemia or Hb SC (Hb SE, Hb SD).
[Causes of sickle cell anemia
The main defect in this pathology is the production of HbS as a result of spontaneous mutation and deletion of the β-globin gene on chromosome 11, which leads to the replacement of valine with glutamic acid in the position of the VIP-polypeptide chain (a 2, β 2, 6 val). Deoxygenation causes the deposition of deoxygenated molecules of anomalous hemoglobin in the form of monofilaments, which, as a result of aggregation, turn into crystals, thereby changing the erythrocyte membrane, which ultimately is accompanied by the formation of sickle cells. It is believed that the presence in the body of the sickle cell anemia gene gives the patient a certain degree of resistance to malaria.
Causes and pathogenesis of sickle cell anemia
Symptoms of sickle-cell anemia
The disease occurs in the form of episodes of painful attacks (crises) associated with the occlusion of capillaries as a result of spontaneous "cirrus" erythrocytes, alternating with periods of remission. Crises can be provoked by intercurrent diseases, climatic conditions, stresses, spontaneous emergence of crises is possible.
Clinical manifestations of the disease usually appear by the end of the first year of life. Fetal hemoglobin (HbF) prevails in newborns, as the concentration of HbS increases in the postnatal period of HbF. Intravascular "surplus" and signs of hemolysis can be detected already at the age of 6-8 weeks, however, clinical manifestations of the disease, as a rule, are not typical until 5-6 months of age.
Diagnosis of sickle cell anemia
In the hemogram, normochromic hyperregenerative anemia is detected - the concentration of hemoglobin is usually 60 ~ 80 g / l, the number of reticulocytes is 50-150%. In the smears of peripheral blood usually contain red blood cells, subjected to irreversible "sickle" - sickle erythrocytes; Aniso- and poikilocytosis, polychromatophilia, ovalocytosis, micro- and macrocytosis are also found, and the Kebot and Jolly bodies are found. The total number of leukocytes is increased to 12-20 x 10 9 / l, neutrophilia is observed; the platelet count is increased, the rate of erythrocyte sedimentation is reduced.
What tests are needed?
Treatment of sickle cell anemia
Transfusion therapy for sickle cell anemia is fraught with increased blood viscosity until the level of Hb S is significantly reduced; Ht should not exceed 25-30% before the beginning of transfusion of erythrocyte mass. Emergency blood transfusion is indicated only if it is necessary to increase the transport function of the blood without a marked decrease in the level of Hb S, for example:
- with severe anemia;
- at sequestration crisis;
- at aplastic crisis;
- in case of blood loss;
- before surgery.
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