Download Chapter 28 Alterations of Hematologic Function in Children
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Chapter 28 Alterations of Hematologic Function in Children
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Fetal and Neonatal Hematopoiesis
The embryo becomes too large for oxygenation by simple diffusion
Erythropoiesis begins within the vessels of the yolk sac At 8 weeks’ gestation, erythrocyte production shifts to the liver sinusoids (peaks at 4 months) By 5 months’ gestation, erythrocyte production begins in the bone marrow • At delivery marrow is only significant hematopoiesis site
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Hemolytic Disease of the Newborn
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Fetal and Neonatal Hematopoiesis
Fetal hemoglobin
Two α-chains; two γ-chains Embryonic hemoglobins • Gower 1, Gower 2, and Portland Fetal hemoglobin • Hb F Greater affinity for oxygen than adult hemoglobin
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Fetal and Neonatal Hematopoiesis
Postnatal changes
Erythrocytes Leukocytes Platelets
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Acquired Disorders of Erythrocytes
Iron deficiency anemia
Most common blood disorder of infancy and childhood • Stored iron: greatest stores are present 4 to 8 weeks after birth • Dietary iron: needed after 16-20 weeks of age
Lack of iron intake or blood loss Manifestations • Irritability, decreased activity tolerance, weakness, and lack of interest in play
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Acquired Disorders of Erythrocytes
Acquired congenital hemolytic anemia
Hemolytic disease of the newborn (HDN) • Alloimmune disease • Maternal antibody directed against fetal antigens • ABO incompatibility occurs in 20% to 25% of cases • Rh incompatibility occurs in less than 10% • Also termed erythroblastosis fetalis
Presence of red cell precursors in the peripheral blood
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Acquired Disorders of Erythrocytes
Hemolytic disease of the newborn (HDN)
Manifestations • Anemia • Hyperbilirubinemia • Icterus neonatorum • Kernicterus Treatment • Prevention: RhoGAM
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Hemolytic Disease of the Newborn
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Acquired Disorders of Erythrocytes
Anemia of infectious disease
Diseases initially acquired by the mother and transmitted to the fetus • Results in hemolytic anemia • Likely due to injury to the erythrocyte membranes or erythrocyte precursors
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Inherited Disorders of Erythrocytes
Glucose-6-phosphate dehydrogenase deficiency (G6PD)
Inherited, X-linked, recessive disorder G6PD: enzyme that helps erythrocytes maintain metabolic processes despite injurious conditions Asymptomatic unless stressors present Without G6PD oxidative stressors damage hemoglobin and the plasma membranes of erythrocytes (Heinz bodies)
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Inherited Disorders of Erythrocytes
Hereditary spherocytosis
Autosomal dominant trait Abnormality of proteins or spectrins of the erythrocyte membrane leading to an increased concentration of intracellular sodium Causes splenomegaly and microcytic spherocytes
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Hereditary Spherocytosis
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Inherited Disorders of Erythrocytes
Sickle cell disease
Disorders characterized by the presence of an abnormal hemoglobin (Hb S) • Mutation causes valine to be replaced by glutamic acid Deoxygenation and dehydration cause the red cells to solidify and stretch into an elongated sickle shape
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Inherited Disorders of Erythrocytes
Sickle cell disease
Once sickling begins, continues until Po2 returns to normal, then it ceases spontaneously Extent, severity, and clinical manifestations of sickling depend on the percentage of hemoglobin that is Hb S
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Inherited Disorders of Erythrocytes
Sickle cell disease
Sickle cell trait • Child inherits Hb S from one parent and Hb A from another
Can result in: • Vasoocclusive crisis (thrombotic crisis), aplastic crisis, sequestration crisis, and hyperhemolytic crisis
Other forms • Sickle cell-thalassemia disease and sickle cell-Hb C disease
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Sickle Cell Disease
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Sickle Cell Disease
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Sickle Cell Disease
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Sickle Cell Disease
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Inherited Disorders of Erythrocytes
Thalassemias
Autosomal recessive disorders Synthesis of the globin chains of the hemoglobin molecule is slowed or defective Major—homozygous inheritance Minor—heterozygous inheritance
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Inherited Disorders of Erythrocytes
In alpha-thalassemia the α-chains are affected; ß-chains in beta-thalassemia
Beta-thalassemia minor Beta-thalassemia major Alpha trait Alpha-thalassemia minor Hemoglobin H disease
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Inherited Disorders of Erythrocytes
Beta-thalassemia minor
Mild to moderate hypochromic-microcytic anemia, mild splenomegaly, bronze coloring of the skin, hyperplasia of bone marrow Usually asymptomatic
Beta-thalassemia major
May be quite ill Severe anemia results in large cardiovascular burden
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Inherited Disorders of Erythrocytes
Alpha-thalassemia minor
Clinical manifestations virtually identical to those of beta-thalassemia minor
Alpha-thalassemia major
Hydrops fetalis Fulminant intrauterine congestive heart failure Fetus has a grossly enlarged heart and liver Diagnosis usually is made post mortem
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Inherited Coagulation and Platelet Disorders
Hemophilias
Serious bleeding disorders Hemophilia A (classic hemophilia) Hemophilia B (Christmas disease) Hemophilia C (factor XI deficiency) von Willebrand disease
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Inherited Coagulation and Platelet Disorders
Congenital hypercoagulability and thrombosis
Thrombophilia Protein C deficiency Neonatal purpura fulminans Protein S deficiency Antithrombin III (AT III) deficiency
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Antibody-Mediated Hemorrhagic Disease
Idiopathic thrombocytopenic purpura
Autoimmune or primary thrombocytopenic purpura
Autoimmune neonatal thrombocytopenia Autoimmune neonatal thrombocytopenia purpura Autoimmune vascular purpura
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Leukemia
Most common malignancy of childhood 80% to 85% are acute lymphoblastic leukemias Cause unclear
Genetic susceptibility, environmental factors, viral infections
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Leukemia
Symptoms
Diagnosis
Pallor, fatigue, petechiae, purpura, bleeding, fever, bone pain Bone marrow aspiration • Blast cell
Treatment
Chemotherapy Radiation
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Leukemia
FAB classification
Acute lymphoblastic leukemias L1, L2, and L2 Acute non-lymphoblastic leukemias M1-7
Immunoclassification
Surface marker identification
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Leukemia
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Lymphoma
Non-Hodgkin lymphoma
Nodular and diffuse
Hodgkin lymphoma
Rare in childhood Infectious mode of transmission Many children with Hodgkin lymphoma demonstrate a high antibody titer to Epstein-Barr virus (EBV)
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