Child with Hematologic Disorder

• Thalassemia major


  A genetic blood disorder characterized by abnormal hemoglobin production, leading to anemia, bone deformities, and other complications
• Lana (4-year-old with thalassemia major)


  • Prominent mandible
  • Wide-spaced upper front teeth from overgrowth of bone marrow centers
  • Bronze skin from frequent blood transfusions (64 in her lifetime)
• Joey (7-year-old with sickle-cell anemia)

  • Growth only in the 5th percentile
  • Had two vaso-occlusive crises in the past year
• Lana's mother asks "Why were our two families so unlucky? What could we do to help our children have better lives?"

  Indicates parents' distress and desire to understand and help their children with hematologic disorders
• Previous chapters described the growth and development of well children. This chapter adds information about the dramatic changes, both physical and psychosocial, that occur when children have a hematologic disorder.
• Key terms


  • agranulocytes
  • allogeneic transplantation
  • autologous transplantation
  • blood dyscrasias
  • erythroblasts
  • erythrocytes
  • erythropoietin
  • granulocytes
  • hemochromatosis
  • hemolysis
  • hemosiderosis
  • hypodermoclysis
  • leukocytes
  • leukopenia
  • megakaryocytes
  • normoblasts
  • pancytopenia
  • petechiae
  • plethora
  • poikilocytic
  • priapism
  • purpura
  • reticulocytes
  • synergeneic transplantation
  • thrombocytes
  • thrombocytopenia
• The blood and blood-forming tissues that make up the hematologic system play a vital role in body metabolism: transporting oxygen and nutrients to body cells, removing carbon dioxide from cells, and initiating blood coagulation when vessels are injured.
• Any alteration in the substance or function of blood or its components can have immediate and life-threatening effects on the functioning of all body systems.
• Hematologic disorders


  Also called blood dyscrasias, occur when components of the blood are formed incorrectly or either increase or decrease in amount beyond normal ranges
• Most blood dyscrasias in children originate in the bone marrow, where blood cells are formed.
• National Health Goals related to blood disorders are shown in Box 44.1.
• Blood dyscrasias do not occur at equal rates in all countries, because many of these disorders are inherited.
• Treatment for blood disorders can be culturally influenced as well.
• For example, families who are Jehovah's Witnesses may refuse blood transfusions, a common therapy for blood disorders, on religious grounds.
• Red blood cells (RBCs)

  Formed under the stimulation of erythropoietin, a hormone produced by the kidneys that is stimulated whenever a child has tissue hypoxia
• Children with kidney disease

  Often have a low number of RBCs because erythropoietin secretion is inadequate in diseased kidneys
• Polycythemia


  An overproduction of RBCs that can occur in children who experience prolonged systemic hypoxia because of erythropoietin overproduction
• RBC formation


  Erythroblasts (large, nucleated cells) -> Normoblast -> Reticulocyte -> Mature, nonnucleated erythrocytes
• Reticulocytes


  Approximately 1% of RBCs are in the reticulocyte stage at all times, an elevated reticulocyte count indicates rapid production of new RBCs
• Absence of nucleus in mature RBC


  Allows for increased space for oxygen transport, but limits life span to around 120 days
• RBC production


  In infants, occurs in red marrow of long bones, in early childhood shifts to ribs, scapulae, vertebrae, and skull bones as yellow marrow replaces red marrow in long bones
• RBC concentration at birth and changes over time

  5 million per cubic millimeter at birth, decreases to 4.1 million by 3-4 months, then slowly increases to adult level of 4.9 million by adolescence
• Hemoglobin


  Complex protein in RBCs that allows oxygen transport, composed of globin (protein) and heme (iron-containing pigment)
• Fetal hemoglobin


  Has special affinity for oxygen, makes up 40-70% of infant's hemoglobin at birth, gradually replaced by adult hemoglobin (hemoglobin A) in first 6 months
• Hemoglobin levels


  Highest at birth (13.7-20.1 g/100 mL), reach low at 3 months (9.5-14.5 g/100 mL), then gradually rise to adult levels (11-16 g/100 mL) by puberty
• Bilirubin formation


  RBC breakdown -> Heme degradation -> Protoporphyrin -> Indirect bilirubin -> Liver converts to direct bilirubin for excretion
• Newborn jaundice


  Caused by immature liver unable to convert indirect to direct bilirubin, leading to high levels of indirect bilirubin permeating outside circulatory system
• Leukocytes (white blood cells, WBCs)


  Nucleated cells, 1 per 500 RBCs, primary function is defense against antigens
• Types of WBCs


  • Granulocytes (neutrophils, basophils, eosinophils)
  • Agranulocytes (lymphocytes, monocytes)
• WBC count


  Newborns ~20,000/mm3, falls to ~12,000/mm3 by 14-30 days, reaches adult level of 5,000-10,000/mm3 by age 4
• Thrombocytes (platelets)


  Nonnucleated bodies formed by bone marrow, function is capillary hemostasis and primary coagulation, normal range 150,000-300,000/mm3 after first year
• Blood coagulation


  Platelet plug formation -> Intrinsic and extrinsic pathways form complete thromboplastin -> Thromboplastin converts prothrombin to thrombin -> Thrombin converts fibrinogen to fibrin
• Blood coagulation factors


  • I Fibrinogen
  • II Prothrombin
  • III Thromboplastin
  • IV Calcium
  • V Labile factor
  • VII Stable factor
  • VIII Antihemophilic factor
  • IX Christmas factor
  • X Stuart factor
  • XI Plasma thromboplastin antecedent
  • XII Hageman factor
  • XIII Fibrin stabilizing factor
• Common tests for blood coagulation include prothrombin time, partial thromboplastin time, bleeding time, clot retraction, tourniquet test, prothrombin consumption time, thromboplastin generation time, plasma fibrinogen, and venous clotting time
• Bone marrow aspiration and biopsy can be painful procedures, requiring local anesthetic and sometimes conscious sedation, with monitoring of vital signs and dressing after the procedure
• Blood transfusions


  Used to treat anemias and immunodeficiencies, can be whole blood, packed RBCs, plasma, platelets, etc., must be carefully matched to patient's blood type and infused with isotonic solution
• A transfusion of 15 mL/kg packed RBCs can be expected to raise the hematocrit level by 5 points, and a platelet transfusion can raise the platelet count by approximately 10,000 cells
• Blood product


  It is important that it has been carefully matched with the child's blood type
• Blood infusion


  Must be accompanied with a solution as nearly isotonic as possible (normal saline)
• If blood is given with a hypertonic solution


  Fluid will be drawn out of the RBCs, causing them to shrink