chapter 10

• Aplastic anemias


  Result from depression of hematopoietic activity in the bone marrow, affecting the formation and development of WBCs, platelets, and RBCs
• Congenital aplastic anemia (Fanconi syndrome)


  Inherited as an autosomal recessive trait, child is born with several congenital anomalies and begins to manifest symptoms of pancytopenia between 4 and 12 years of age
• Acquired aplastic anemia


  Decrease in bone marrow production that can occur from exposure to radiation, drugs, or chemicals known to cause bone marrow damage
• Hypoplastic anemias


  Also result from depression of hematopoietic activity in bone marrow, but only RBCs are affected
• Congenital hypoplastic anemia (Blackfan-Diamond syndrome)


  Rare disorder that shows symptoms as early as the first 6 to 8 months of life, affects both sexes and is apparently caused by an inherent defect in RBC formation
• Treatment for congenital hypoplastic anemia


  1. Increased erythropoiesis with corticosteroid therapy

  2. Long-term transfusions of packed RBCs to raise erythrocyte levels

  3. Iron chelation program with subcutaneous infusion of deferoxamine to bind and excrete excess iron
• Acquired hypoplastic anemia


  Reduction of RBCs is transient, so no therapy is necessary
• Iron-deficiency anemia


  Most common anemia of infancy and childhood, occurring when the intake of dietary iron is inadequate
• Children are at high risk for iron-deficiency anemia because they need more daily iron in proportion to their body weight to maintain an adequate iron level than do adults</b>
• Iron-deficiency anemia occurs most often between ages 9 months and 3 years, and its frequency rises again in adolescence</b>
• Infants of low birth weight have fewer iron stores than those born at term because iron stores are laid down near the end of gestation</b>
• Prevention of iron-deficiency anemia


  1. Iron-fortified formula for formula-fed infants

  2. Iron-fortified cereal introduced with solid foods for breastfed infants
• Anemia of folic acid deficiency


  Deficiency of folic acid combined with vitamin C deficiency produces an anemia with abnormally large erythrocytes, often accompanying neutropenia and thrombocytopenia
• Pernicious anemia (vitamin B12 deficiency)


  Vitamin B12 is necessary for maturation of RBCs, deficiency or inability to use the vitamin results in pernicious anemia
• In children, the cause of pernicious anemia is more often lack of ingestion of vitamin B12, found primarily in foods of animal origin</b>
• Treatment for pernicious anemia

  1. Temporary injections of B12 if caused by B12-deficient diet

  2. Lifelong monthly intramuscular injections of B12 if caused by lack of intrinsic factor
• Sickle-cell anemia


  Autosomal recessive inherited disorder on the beta chain of hemoglobin, causing abnormally shaped (elongated) RBCs that become sickled under certain conditions
• Sickle-cell disease is usually not clinically apparent until a child's hemoglobin changes from the fetal to the adult form at approximately 6 months</b>
• Children with sickle-cell anemia


  • Tend to have a slight build with characteristically long arms and legs, may have a protruding abdomen from enlarged spleen and liver
• Management of sickle-cell disease


  1. Receive childhood immunizations to prevent infections

  2. May be prescribed oral penicillin as prophylaxis for first 5 years

  3. Avoid contact sports and long-distance running

  4. Maintain hydration, especially in summer and during air travel
• Sickle-cell crisis


  Sudden, severe onset of sickling symptoms from pooling of sickled cells in vessels and consequent tissue hypoxia
• Sickle-cell crisis can occur with illness causing dehydration, respiratory infection, or strenuous exercise</b>
• Thalassemias


  Autosomal recessive anemias associated with abnormalities of the beta chain of adult hemoglobin
• Thalassemia minor


  Mild form where child produces both defective beta hemoglobin and normal hemoglobin, requires no treatment and has normal life expectancy
• Thalassemia major (Cooley's anemia or Mediterranean anemia)


  Severe form where child is unable to produce normal beta hemoglobin, resulting in symptoms of anemia
• Thalassemia minor


  Mild form of thalassemia, no treatment required, normal life expectancy
• Thalassemia minor individuals should not receive routine iron supplements as they cannot incorporate it well into hemoglobin and may accumulate too much iron
• Thalassemia major


  Also called Cooley's anemia or Mediterranean anemia, a beta chain hemoglobin defect where symptoms become apparent as fetal hemoglobin is replaced by adult hemoglobin
• Symptoms of thalassemia major include anemia, pallor, irritability, and anorexia
• Red blood cells in thalassemia major


  • Hypochromic (pale), microcytic (small), fragmented poikilocytes, basophilic stippling

  
• Hemoglobin level is less than 5 g/100 mL in thalassemia major, serum iron level is high due to inability to incorporate it into hemoglobin, iron saturation is 100%
• Most disorders of white blood cells occur in response to another disease, often infection or allergic reaction, and provide objective indicators of infectious disease

  
• Thrombocytopenia


  Decreased platelet count, defined as less than 40,000/mm3, often leads to purpura (blood seeping from vessels into skin)
• TAR (thrombocytopenia/absent radius) syndrome is a rare disorder where children are born with thrombocytopenia and missing the radius bone in the forearm
• Idiopathic Thrombocytopenic Purpura (ITP)


  Decrease in circulating platelets due to increased platelet destruction from an antiplatelet antibody, an autoimmune illness
• ITP often occurs 2 weeks after a viral infection, and can also occur in newborns of mothers who had ITP during pregnancy
• Manifestations of ITP


  • Petechiae, ecchymosis, epistaxis, joint bleeding, marked thrombocytopenia (platelet count as low as 20,000/mm3), normal megakaryocytes in bone marrow
• Treatment of ITP


  Oral prednisone, intravenous immunoglobulin (IVIG), anti-D immunoglobulin, platelet transfusion (temporary effect)
• Acetaminophen rather than salicylates or ibuprofen is prescribed for pain in ITP to avoid increased bleeding risk
• Most children with ITP have a limited 1-3 month course, some develop chronic ITP requiring immunosuppressive drugs