Sickle cell disease

Introduction to sickle cell disease Sickle cell disease (sicklecelldisease) refers to an autosomal dominant hemolytic disease in which red blood cells contain hemoglobin S (HbS). There are three types of this disease: homozygous 1HbS is called sickle cell anemia; 2 heterozygotes Called a sickle celltrait; a double heterozygote of 3HbS combined with thalassemia or other abnormal Hb genes is called mixed sickle cell syndrome. The disease is more common in blacks in Africa and the Americas. It is not uncommon in Greece, Turkey, the Middle East and India. This disease is extremely rare in China. In 1975, 3 cases of adult patients were found in a family in Foshan, Guangdong Province. Two cases were characterized by sickle cells, and one was sickle cells/ thalassemia, which were both Chinese and African. basic knowledge The proportion of illness: 0.005% Susceptible people: good for infants and young children Mode of infection: non-infectious Complications: anemia

Causes of sickle cell disease

Homozygous has sickle cell anemia (about 0.3% of black Americans); heterozygotes (8% to 13% of blacks) have no anemia, but the genetic characteristics of this sickle cell in vitro (sickle cell blood) Symptoms) can be displayed.

In the case of HbS disease, the glutamic acid on the 6th amino acid of the chain is replaced by proline, which reduces the charge, making it move toward the anode slower than HbA during electrophoresis, compared with deoxygenated HbA, deoxygenation HbS is much less soluble, and it forms a semi-solid gel of rod-like crystal aggregates, thus forming red blood cells in a low-oxygen partial pressure, forming a sickle-like shape, and twisting and deforming red blood cells, which adhere to the vascular endothelium. And occlusion of small arteries and capillaries to form obstruction and infarction, because the sickle cells are too weak to withstand mechanical damage in the circulation, so when they enter the circulation, hemolysis occurs.

Sickle cell disease prevention

The disease is a hereditary disease, which can only prevent or reduce complications, preventive use of antibiotics, early diagnosis and treatment of severe bacterial infections, and continuous oral penicillin prophylaxis since 4 months of age. Mortality is reduced, especially in childhood.

Sickle cell disease complications Complications anemia jaundice

Common complications of this disease:

1. Chronic anemia.

2. Huang Wei.

3. Acute chest syndrome.

Symptoms of sickle cell disease Common symptoms Joint pain Back pain Myalgia refers to (toe) Osteoinfarction Fatigue Abdominal pain Hematuria Dehydration Unconscious

Symptoms often decrease in fetal Hb (HbF) after 4 months of age, HbS rises, and the number of sickle cells increases. On the one hand, it shows chronic hemolytic anemia. Usually there is a relatively constant mild anemia with light sclera. Yellow staining, liver light, moderate swelling, infants and young children can see splenomegaly, with age, the spleen shrinks due to fibrosis, when cold, infection, dehydration, anemia symptoms increase, yellow staining also deepens, on the other hand due to capillaries Microthrombus causes pain crisis, infants and young children's fingers (toes), hands (foot) back swelling and pain, children and adults with limb muscle pain, large joint pain and low back pain are more common, in addition to severe abdominal pain, headache, Even coma and limb paralysis, etc., can cause anemia crisis when severe infection, manifested as acute hemolysis and sharp increase of spleen, can die in a short period of time, occasionally aplastic anemia crisis, long-term diseased liver, spleen, kidney Chronic organ damage, bones and joints, skin, etc., patients are thin, fatigue, easy to infect various diseases, with malnutrition, poor symptoms of thalassemia - thalassemia similar to poverty, poor symptoms - HbC symptoms are mild, sickle cell Levy a small, but visible haematuria and hypotonic urine.

Examination of sickle cell disease

Laboratory inspection

Erythrocytes are normal cell-like, the count is usually 2000000~3000000/l; hemoglobin is proportionally reduced, and the average red blood cell volume is reduced to provide a basis for -thalassemia. Dry-stained blood slices can only show a small amount of sickle-shaped red blood cells, which can make a diagnosis. It is characterized by the appearance of sickle-shaped red blood cells (crescent-shaped red blood cells, often with long or acute-angled tails) in unstained blood drops, which are treated with anti-drying or treated with a reducing agent such as sodium metabisulfite. This can also be produced by reducing the oxygen tension. This environment can be formed by sealing the blood drops under the coverslip with Vaseline. Then, under the microscope, the rapid test tube test based on the different solubility of HbS has been widely used for screening. .

There are often nucleated red blood cells in the peripheral blood; reticulocytes often increase by 10% to 20%, during the crisis or bacterial infection, leukocytosis can reach 35000/l, and there is a left shift phenomenon, and platelets usually increase. Myeloid hyperplasia, mainly red blood cells, but can become aplastic disorder in sickle cell crisis or severe infection, serum bilirubin is usually increased, urinary bilirubin is high in feces and urine, and erythrocyte sedimentation rate is lowered.

In the electrophoresis, only HbF with different amounts of HbS can be diagnosed as a homozygous state. For example, when HbA and HbS (HbA is more than HbS) are found in electrophoresis, it can be judged as heterozygous, and HbS must be electrophoresed with others. Similar mobile HbS is identified, which can be judged according to the phenomenon of metamorphosis, because other HbS with similar mobility in electrophoresis does not have this phenomenon. This identification is important for genetic counseling, and the application of polymerase chain reaction technology is significantly improved. Sensitivity of prenatal examination.

Diagnosis and differentiation of sickle cell disease

diagnosis

According to clinical manifestations and laboratory data, it is not difficult to diagnose.

Differential diagnosis

Sickle cell disease needs to be differentiated from other abnormal hemoglobin diseases, mainly by hemoglobin electrophoresis.

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