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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