Hereditary spherocytosis (HS) is a hemolytic anemia with congenital defects in the red blood cell membranes, mainly manifesting as anemia, jaundice, and splenomegaly. The disease is inherited from both men and women and occurs in every generation, which is also known as “autosomal dominant”. The age of onset and severity of the disease varies widely, with most cases occurring in early childhood and children. If the disease develops in newborns or infants under the age of 1 year, it is usually more severe. Hereditary spherocytosis (HS) is a form of hemolytic anemia in which there is a congenital defect in the red blood cell membrane. It is characterized by anemia, jaundice, splenomegaly, and increased spherocytosis in the blood, with a chronic anemic course and recurrent acute episodes of hemolysis. The disease is found all over the world, with an incidence of 20-30/100,000 people. This disease is not rare in China, hundreds of cases have been reported in our literature, and Beijing Children’s Hospital has treated 170 cases of HS since its establishment to 1990, the actual number of cases should be more than this. Hereditary spherocytosis Hereditary spherocytosis, also known as congenital hemolytic jaundice, is an anemia caused by defects in the red blood cell membrane. In normal conditions, red blood cells have a flat shape with a thin center and thick periphery, somewhat like a disc. In hereditary spherocytosis, however, the red blood cells become round and spherical. When blood enters the spleen, the red blood cells cannot pass through the tiny blood vessels well, and as a result, many red blood cells remain in the spleen and are destroyed, resulting in hemolysis and anemia. In hereditary spherocytosis (HS), red blood cells lose their normal two-sided concave disc shape and become spherical, i.e., the diameter of the cells is smaller than normal and the area-to-volume ratio is reduced. The deformability of the seed cells is significantly reduced and they do not pass easily in the splenic sinus, and hereditary spherocytosis results in destruction in the spleen. Some studies have shown that the morphology and physical properties of naive erythrocytes in the bone marrow are quite normal, but after the erythrocytes are released from the bone marrow and become orbicular-spherocytes under electron microscopic observation, only about 5% of the cells are true spherocytes. Alterations in the chemical composition of the erythrocyte membrane Alterations in the chemical composition of the spherical cell membrane underlie changes in cell morphology and metabolic function, yet the molecular chemistry of the defective HS cell membrane has not been elucidated to date. Studies have shown that total lipids are reduced in HS cells, but the relative proportions of cholesterol, total phospholipids, and each phospholipid component are not abnormal; the scaffolding proteins of HS cell membranes are abnormal. There may be several different alterations that can lead to the formation of spherocytes. Hereditary spherocytosis Altered metabolic function of erythrocytes Under normal conditions, plasma Na+ is about 12 times higher than the concentration of Na+ in the erythrocytes, and it can slowly permeate through the erythrocyte membrane by diffusion and enter the cells. With the permeation of Na+, water enters. Erythrocytes must rely on their sodium pump (Na-K-ATPase) to continuously excrete the permeated Na+ and water out of the cell to maintain the balance of cations and water inside and outside the cell. hs cells have a faster rate of Na+ permeation into the cell and a higher amount of entry due to a functional defect in the membrane. In order to maintain a constant intracellular Na+ concentration, the activity of the sodium pump to excrete intracellular Na+ must be intensified. This cellular metabolic activity requires adenosine triphosphate (ATP) to supply energy. ATP in erythrocytes is derived from the anaerobic enzymolysis of intracellular glucose. Therefore, the process of intracellular glucose enzymolysis is accelerated, cellular glucose consumption is accelerated, and lactate production is increased. It has been shown that the total rate of glycolysis in HS cells is 20% to 30% above normal. This is a compensatory effect for the increased Na+ permeability of the cytosolic membrane. However, since the basic defect is not in the sodium pump or glycolysis itself, and the source of glucose in the erythrocytes is limited to meet the demands of the high metabolic mass consumption of the cells, finally the lack of glucose leads to a decrease in the production of ATP, a difficult excretion of Na+ and water and stagnation, and a swelling of the cytosol into a spherical shape. When such spherical cells flow through the spleen, they are retained and destroyed at the splenic sinus. Hereditary spherocytosis In vitro, this functional defect in erythrocytes can be seen in the osmotic fragility test. During the first 12 hours of warming in hypotonic saline, intracellular glucose is gradually consumed and the ATP content decreases, as a result of which the erythrocytes lose the ability to control their volume; within 24 hours, the Na+ entering the erythrocytes exceeds the K+ escaping from the erythrocytes, resulting in increased water entry into the cells, increased osmotic pressure, increased erythrocyte volume, and increased osmotic fragility. In vitro incubation to 24-48 hours after the complete loss of membrane control cation permeability, the concentration of cations in the erythrocyte and the pericellular medium tends to equilibrate, K+ loss is significant, phosphate and many intermediate products of sugar decomposition is also lost, the result is a reduction in cell volume, and finally hemoglobin can also escape from the erythrocyte, at which point the “autolysis of blood The phenomenon of “autolysis” occurs. The role of the spleen in destroying spherocytes Studies have shown that the defect in HS cells is in the red blood cells themselves, and that the site of destruction is mainly the spleen, which is functioning normally. Hereditary spherocytosis In the microcirculation of the spleen, the abnormal deforming properties of HS cells make it particularly vulnerable to destruction. The diameter of normal erythrocytes is about 8 μm, while the narrowest point in the microcirculation of the splenic sinus is only 3 μm on average. normal erythrocytes can pass smoothly due to their high deformability, while HS cells are spherical and have poor deformability, and when entering the microcirculation of only 3 μm, they can hardly pass and are blocked and stagnated in the splenic medulla. In the splenic marrow, the supply of glucose is reduced and the oxygen tension and pH are low, which makes the cells become more rigid and finally phagocytosed and destroyed by macrophages in the spleen. Even though some of the spherical cells pass through the splenic sinus with difficulty, they lose part of their cell membrane, which further reduces the area of the cell membrane and makes the cells more spherical and more vulnerable to destruction when they flow through the spleen again later. Clinical manifestations The majority of the disorders are autosomal dominant, with a very small number being autosomal recessive. It can occur in both sexes. The autosomal dominant form is characterized by anemia, jaundice and splenomegaly. The disease is classified into the following three types according to the severity of the disease: ① Light type, mostly seen in children, accounts for about 1/4 of all cases of hereditary spherocytosis, and may have no or only mild anemia and splenomegaly due to good bone marrow compensatory function; ② Intermediate type, accounting for about 2/3 of all cases, mostly develops in adults, with mild to moderate anemia and splenomegaly; ③ Heavy type, with only a few patients, has severe anemia, often depends on blood transfusion, growth retardation, facial bone structure (iii) only a few patients with severe anemia, often dependent on blood transfusions, growth retardation, facial bone structure changes similar to marine anemia, and occasionally or several times a year, hemolytic or aplastic crisis. Those with autosomal recessive inheritance also tend to have significant anemia and giant spleen with frequent jaundice. Hemolytic or aplastic crisis is often triggered by infection, pregnancy, or emotional stress. Patients have chills, high fever, nausea and vomiting, and acute anemia that lasts for several days or even 1 to 2 weeks. The more common complication in patients with this disease (about 50%) is cholelithiasis due to excessive bilirubin excretion and precipitation in the bile ducts, followed by chronic ulcers in the legs occurring above the ankle, which often persist but can be cured by splenectomy. Developmental abnormalities or mental retardation are rare. Laboratory tests Unless there is an acute attack, anemia is usually not severe, but hemoglobin may be as low as about 3 g/dl in critical cases. Some erythrocytes (20% to Hereditary spherocytosis 30%) are small in diameter but thicker than normal and appear small and darkly stained in the smear, so MCV is mildly reduced and MCHC is increased. Reticulocytes are often between 5% and 20% and can be as high as 0-70% after an acute episode of hemolysis, with a few young red blood cells in the blood. The osmotic fragility of erythrocytes in hypotonic saline solution is enhanced with the increase of spherical erythrocytes. The shape of the curve of the fragility test varies. When a significant number of erythrocytes are spherical, most of the curve shifts to the right of the normal curve. If there are not many spherical cells, the fragility test curve can still be in the normal range, but its tail is in a higher concentration of saline. Incubation of the patient’s red blood cells for 24 hours followed by a fragility test may show increased osmotic fragility even in very mild patients (Figure 20-8). A positive autologous hemolysis test can be corrected with the addition of glucose. The bone marrow mostly shows normal juvenile erythropoietic signs. Total serum bilirubin ranges from 17.1 to 68.4 μmol/L. When aplastic crisis occurs; the red blood cell count decreases sharply, but reticulocytes disappear instead. Total serum bilirubin does not necessarily increase but decreases. Young red blood cells in the bone marrow are poorly produced or even maturation is halted. A few cases may be associated with leukopenia and thrombocytopenia. Diagnosis and Differentiation Hereditary spherocytosis is a hemolytic anemia with defective erythrocyte membranes. The determinants of erythrocyte destruction in this disease are: intrinsic defects in erythrocytes and the spleen as a site of aggravated erythrocyte destruction. It is characterized clinically by anemia, intermittent jaundice and splenomegaly of varying degrees. 1. The blood picture shows orthocytic orthochromic anemia. A marked increase in spherical erythrocytes is its main feature. Reticulocytes are increased, but decreased in critical conditions. The leukocytes are normal or slightly increased, and the neutrophils may be increased and the nuclei may be left shifted. 2. The bone marrow picture shows juvenile erythrocyte hyperplasia. Small spherical mature erythrocytes can be seen, and the size of erythrocytes is uneven. Scanning electron microscopy can be seen erythrocytes of unequal size, most of the erythrocyte surface is not smooth, often with micro-bumps, disc-shaped erythrocyte depression becomes shallow. 3, other: erythrocyte permeability internal organs test can be seen increased fragility, warm incubation after the permeability fragility test is also seen to enhance its permeability test, positive autohemolysis test Treatment The main method of treatment of hereditary spherocytosis is splenectomy. Splenectomy is the most effective treatment for complete and lasting remission of the anemia. After splenectomy, although the defects in the erythrocyte membrane and spherocytosis remain, and the osmotic fragility remains abnormal, excessive hemolysis ceases and the survival time of the erythrocytes approaches normal, so the anemia disappears. Splenectomy is recommended in all cases with a clear diagnosis, except for those with contraindications to surgery. Recurrence of anemia after surgery is extremely rare. The best time for surgery is after the age of 7 years, but if the anemia is particularly severe, requiring frequent blood transfusions and affecting the development of the child, earlier surgery can be considered. Before splenectomy, a cholecystogram should be done to find out if there are gallstones in the gallbladder. During splenectomy, the gallbladder is then carefully explored. If stones are found, appropriate surgical management can be done at the same time. If no gallstones are found, cholecystectomy is not necessary. In patients with hereditary spherocytosis who have not undergone splenectomy, hemolytic crisis is treated by blood transfusion and treatment of the infection that induced the hemolysis. The occurrence of bone marrow aplasia crisis is also associated with infection, and its treatment is also blood transfusion and infection control. After the disease improves, splenectomy should also be performed. If megaloblasts appear in the bone marrow, oral folic acid 5 to 10 mg daily can be given. 1. Splenectomy it can reduce anemia in most HS and bring reticulocytes close to normal (down to 1%-3%) For most heavy HS, it can improve symptoms significantly, although it cannot completely relieve. Generally, jaundice subsides and hemoglobin increases several days after spleen excision; erythrocyte lifespan is prolonged but does not completely return to normal; peripheral blood small spherical erythrocyte morphology and number do not change MCV may decrease and MCHC remains elevated; white blood cells and platelets increase. Although significant results can be achieved after splenectomy in HS patients, splenectomy can also produce many complications, and some patients die from post-splenectomy infection of the mesentery or portal vein occlusion. The most important complication is infection, especially in infants and children; Singer et al. 1973 reported sepsis in 30 (3.52%) of 850 splenectomy cases (786 of which were children, most of whom were operated on under 5 years of age), of which 19 (3.5%) died. The mortality rate was 200 times higher than that of the general population. Most of the patients were under 1 year of age who underwent splenectomy, but older children and adults were not uncommon. Schwartz and Green separately counted the incidence of infection after splenectomy in adults: the annual incidence of fulminant sepsis was 0.2% to 0.5%, with an annual mortality rate of 0.1%; the annual incidence of other bacterial infections such as pneumonia, meningitis, inflammatory peritonitis, and inflammatory bacteremia was 4.5%, significantly higher than in the general population, with infections generally occurring within 2 years after surgery. Another complication after splenectomy is a significantly higher incidence of ischemic heart disease (1.86 times higher than in the general population) the cause of which health search is unclear. It may be related to the increase in platelets after surgery. It is important to strictly control the indications for splenectomy, especially in infants and children. The indications for splenectomy in HS advocated abroad are: ① Heavy HS with Hb ≤ 80g/L and reticulocytes ≥ 10%. ② If Hb is 80-110g/L and reticulocytes are 8%-10%, splenectomy should be considered for those with one of the following conditions: A. Anemia affecting quality of life or physical activity; B. Anemia affecting the function of important organs; C. Extramedullary hematopoietic masses. ③Age restriction: It is advocated to operate after 10 years of age, and for heavy HSma, the timing of surgery is also delayed to above 5 years of age as much as possible, and surgery under 2-3 years of age is avoided as much as possible; for those who have recurrent remitting crisis or depend on blood transfusion for maintenance and have to undergo splenectomy, pneumococcal vaccine and prophylactic antibiotic treatment should be given. The reasons for failure of splenectomy are: ① the presence of a parasplenium; ② the formation of a regenerating spleen due to splenic tissue implanted in the abdominal cavity as a result of splenic rupture during surgery. This usually occurs several years (or even more than 10 years) after the splenectomy has achieved efficacy and then hemolysis occurs; ③ special heavy HS; ④ wrong diagnosis or concurrent other hemolytic diseases such as G-6-PD deficiency. For all splenectomized patients, pneumococcal triple vaccine should be given, preferably several weeks before surgery, especially in adolescent patients. However, in infants under 2 years of age, the role of the vaccine in preventing infection is not certain. Prophylactic antibiotic therapy focusing on the prevention of pneumococcal sepsis is generally recommended for splenectomized patients and can be applied with oral penicillin (dose of 125 mg twice/d orally for children under 7 years of age; dose of 250 mg twice/d orally for children over 7 years of age and adults), which should be continued for 2 to 5 years after surgery. However, in view of the toxic side effects of antibiotics, bacterial resistance and economic problems, so the prophylactic antibiotic treatment is still controversial should be selected according to the specific situation and the best program. 2. Folic acid supplementation 1mg/d orally. Blood transfusion should be given for severe hemolysis. Examination protocol Laboratory examination 1. General examination of anemia is mostly moderate, but in case of crisis, hemoglobin can drop very low, while in non-acute attacks it can be close to normal. Spherocytosis is the most prominent manifestation. In blood film such cells are small in diameter, round, stain darker than normal and lack a central lightly stained area. The mean erythrocyte volume (MCV) is normal or slightly lower, the mean hemoglobin (MCH) is normal, and the mean hemoglobin concentration (MCHC) is increased to 34% to 40%. Reticulocyte count is often increased, mostly between 5% and 20%, even when anemia is not obvious. When reticulocytes are high, a few late juvenile red blood cells are often seen in the blood film. The white blood cell count is normal or mildly elevated. Platelet count is normal. 2, special test osmotic fragility test: This is an effective method for quantitative determination of the degree of sphericity of red blood cells. Spherical cells have increased fragility in hypotonic saline and are more prone to hemolysis than normal red blood cells. The principle of this test is to mix red blood cells suspended in different concentrations of sodium chloride solution. Water enters the red blood cells in the low concentration of sodium chloride solution, causing the cells to swell and eventually hemolysis to occur. The degree of hemolysis can be estimated by measuring the optical density with a spectrophotometer. Hemolysis of normal erythrocytes begins at a concentration of 0.45% to 0.50% NaCl. hemolysis of HS (and other hemolytic anemias with spherical cells) begins at 0.70% or even higher concentrations of NaCl solution. Warming osmotic fragility test: If blood is incubated sterilely at 37°C for 24 hours, the osmotic fragility of red blood cells will increase significantly. The osmotic fragility of both normal erythrocytes and HS erythrocytes is increased because of the accelerated metabolism and consumption of glucose and ATP in the erythrocytes during warming. The difference in osmotic fragility between HS spherical cells and normal erythrocytes is more pronounced, and HS cells may start hemolysis in 0.80% NaCl solution. the osmotic fragility test results of HS light erythrocytes can be normal, but after warming, it can be detected. Autolysis test (type I): Red blood cells are gradually hemolyzed when placed in their own plasma or serum and warmed at 37°C. This may be related to partial loss of membrane and inability to maintain cation balance. Making an autolysis test (type I) is also valuable for the diagnosis of HS. It is performed by adding or not adding glucose to plasma or serum, and then adding red blood cells for warming at 37℃ for 48 hours to observe the degree of hemolysis. Under the condition of adding glucose first, the hemolysis of normal red blood cells is <0.6%, while the hemolysis of hs red blood cells can generally be reduced to 3%-6%, although there can be exceptions. Under the condition of not adding glucose, the hemolysis of normal erythrocytes is generally <4%, while the hemolysis of erythrocytes in hs patients increases to 10%-30%. 3. Other tests increase serum indirect bilirubin, but not direct bilirubin, during episodes of jaundice. The anti-human globulin test (Coombs test) was negative. The survival time of erythrocytes is significantly shortened, T1/2 (51Cr) is usually 4-8 days, and the increased radioactivity on the surface of the splenic area indicates increased destruction of HS cells in the spleen. There is an increase in the proliferation of erythrocyte lineage in the bone marrow, in which middle and late juvenile erythrocytes predominate, accounting for 25% to 60% of all nucleated cells, and mitotic signs are common. When "aplastic crisis" occurs, there is a significant decrease in the red lineage cells, as well as a significant decrease in reticulocytes in both bone marrow and peripheral blood. The application of modern molecular biology techniques can detect membrane protein abnormalities at the molecular level. For example, RFLP or tandem repeat number analysis (RNTR) can determine the correlation between HS and a certain gene, and single strand conformation polymorphism analysis (SSCP) polymerase chain reaction (PCR) combined with nucleotide sequencing can detect the mutation point of membrane protein gene. Serum bilirubin is increased mainly by indirect bilirubin, mostly in the range of (27.4±18.8) μmol/L. Serum conjugated bead protein is decreased and lactate dehydrogenase is increased. coombs test is negative bone marrow image of red lineage cell hyperplasia, with nucleated red blood cells up to 25-60%. Serum folate level is generally decreased. 3, according to the condition, clinical manifestations signs and symptoms choose to do ultrasound, electrocardiogram, X-ray and other tests. There are two types of inheritance in hereditary spherocytosis 1, autosomal dominant inheritance, with short arm deletion of chromosome 8, common, spleen removal treatment is effective. 2, autosomal recessive inheritance, is a rare type found in recent years, spleen excision is only partially effective, and such cases have been seen throughout China. The pathogenesis of the patient's erythrocyte membrane skeleton proteins such as blood shadow protein, anchor-linked membrane protein, band III protein, etc. have abnormalities, the membrane's passive sodium inflow permeability increases, water enters the cell with sodium salt, so that the concave disc-shaped cell surface area decreases, gradually becomes smaller and thicker, close to the sphere. In order to maintain the normal ratio of sodium and salt concentration inside and outside the cell, more adenosine triphosphate (ATP) needs to be produced to accelerate sodium excretion and potassium intake. Therefore, the glycolytic rate of spherical cells tends to increase by 20% to 30% compared to normal erythrocytes to compensate for the large amount of ATP consumption. The relative lack of ATP causes inhibition of calcium-active ATPase in the membrane and calcium is easily deposited on the membrane. The actomyosin in the cytosolic membrane changes from a lysin to a gel, and thus the erythrocyte membrane becomes stiff and loses flexibility. Although the diameter of the spherical cells is less than 6μ, they cannot enter the splenic sinus through the endothelial intercellular space (only about 3μ in diameter) because of the reduced deformability and flexibility of the cell membrane. During the retention of a large number of erythrocytes in the splenic cord, ATP and glucose are further depleted and the metabolic defects are exacerbated, leading to destruction and lysis. Clinical manifestations The majority of the disease is autosomal dominant, and a very small number are autosomal recessive. It can occur in both sexes. The autosomal dominant form is characterized by anemia, jaundice and splenomegaly. The disease is classified into three types according to the severity of the disease: (1) mild type, mostly seen in children, accounting for about 1/4 of all cases, may have no or mild anemia and splenomegaly due to good bone marrow compensation; (2) intermediate type, accounting for about 2/3 of all cases, mostly develops in adults, with mild to moderate anemia and splenomegaly; (3) heavy type, only a small number of patients, with severe anemia, often dependent on blood transfusion, growth retardation, facial bone structure changes similar to marine anemia, and occasionally or several times a year. Occasionally or several times a year, hemolytic or aplastic crises occur. Autosomal recessive patients also tend to have significant anemia and giant spleen, with frequent jaundice. Hemolytic or aplastic crisis is often triggered by infection, pregnancy, or emotional stress. Patients have chills, high fever, nausea and vomiting, acute anemia, and reticulocytopenia that lasts for several days or even 1 to 2 weeks. The more common complication in patients with this disorder (about 50%) is cholelithiasis due to excessive bilirubin excretion and precipitation in the bile ducts, followed by chronic ulcers in the legs occurring above the ankle, which often persist but can be cured by splenectomy. Developmental abnormalities or mental retardation are rare.