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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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