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Alterations of Hematologic Function in ChildrenChapter 28

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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 By the fifth month of gestation, erythrocyte

production begins to occur in the bone marrow

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Hemolytic Disease of the Newborn

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Fetal and Neonatal Hematopoiesis Fetal hemoglobin

Two alpha chains; two gamma chains Embryonic hemoglobins

Gower 1, Gower 2, and Portland

Fetal hemoglobin Hgb F

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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

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 incompatability occurs in 20% to 25% of cases Rh incompatibility occurs in less than 10% Also termed erythroblastosis fetalis

Presence of red cell precursors on the peripheral blood

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Acquired Disorders of Erythrocytes Hemolytic disease of the newborn (HDN)

Manifestations Anemia Hyperbilirubinemia Icterus neonatorum Kernicterus

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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 is an enzyme that helps erythrocytes

maintain metabolic processes despite injurious conditions

Asymptomatic unless stressors are present

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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 (Hgb 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

Sickle cell trait Child inherits Hgb S from one parent and Hgb 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 alpha chains are

affected; beta chains in beta thalassemia Beta-thalassemia minor Beta-thalassemia major Alpha trait Alpha-thalassemia minor Hemoglobin H disease

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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 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)