HEMA IN PEDIA ETC

• HCT (%)

  Hematocrit
• WBCs (X10^9/L)

  White blood cells
• RBCs (X10^12/L)

  Red blood cells
• HGB (g/dL)

  Hemoglobin
• MCV (FL)

  Mean corpuscular volume
• WBC differential

  Percentage of neutrophils and lymphocytes
• RBC morphology

  • Macrocytic with slight to moderate polychromasia
  • 7 NRBCs/100 WBCs
• Hematology and hemostasis values are fairly stable throughout adult life, but significant differences exist in the pediatric and, to some extent, the geriatric and pregnant populations.
• Children are not merely "small adults." The newborn infant, older child, and adult exhibit profound hematologic differences from one another.
• Pediatric hematology has emerged as a specialized science with age-specific reference intervals that correlate with the hematopoietic, immunologic, and chemical changes in a developing child.
• Prenatal hematopoiesis

  1. Mesoblastic (yolk sac)

  2. Hepatic (liver)

  3. Myeloid (bone marrow)
• Hematopoietically active bone marrow is referred to as red marrow, as opposed to inactive yellow (fatty) marrow.
• At the time of birth, the bone marrow is fully active and almost completely cellular, with all hematopoietic cell lineages undergoing cellular differentiation and amplification.
• Extramedullary hematopoiesis may be seen in times of stress, most commonly in the liver, spleen, lymph nodes, and paravertebral regions.
• Pediatric developmental stages

  • Neonatal period (first 4 weeks of life)
  • Infancy (first year of life)
  • Childhood (age 8 to 12 years)
• Gestational age and birth weight categories

  • Full-term (37-42 weeks)
  • Preterm/premature (<37 weeks)
  • Postterm (>42 weeks)
  • Appropriate size for gestational age
  • Small for gestational age (≤2500g)
  • Very low birth weight (≤1500g)
  • Extremely low birth weight (≤1000g)
  • Large for gestational age (>4000g)
• Factors affecting neonatal hematologic values

  • Gestational age
  • Birth weight
  • Age in hours after delivery
  • Presence of illness
  • Level of support required
  • Site of sampling and technique
  • Timing of sampling
  • Course of labor
  • Treatment of umbilical vessels
  • Maternal drug use
• Polycythemia of the newborn

  Increase in RBC count during the first 24 hours of life, remains at this plateau for about 2 weeks, then slowly declines
• Physiologic anemia of the neonate

  Decrease in hemoglobin concentration, RBC count, and reticulocyte percentages during the first 5-8 weeks of life
• Erythrocyte morphology of the neonate

  • Early normoblasts are megaloblastic, hypochromic, and irregularly shaped
  • Erythrocytes remain macrocytic from first 11 weeks of gestation until day 5 of postnatal life
  • Orthochromic normoblasts often identified on first day of life but disappear within 3-5 postnatal days
• Reticulocyte count


  Apparent reticulocytosis during gestation, decreasing from 90% at 12 weeks to 15% at 6 months and 4-6% at birth<|>Reticulocytosis persists for 3 days after birth then declines abruptly to 0.8% on days 4-7
• Hemoglobin

  Hb F constitutes 53-95% of total Hb at birth, declines to 7% at 12 weeks and 2-3% by 6 months<|>Hemoglobin concentration fluctuates dramatically in weeks/months after birth due to physiologic changes
• The lifespan of erythrocytes in term neonates is 60-70 days, compared with 35-50 days for premature neonates.
• Physiologic anemia of the neonate

  Hemoglobin concentration of term infants decreases during the first 5 to 8 weeks of life
• Physiologic anemia of prematurity

  Infants born prematurely experience a decrease in hemoglobin concentration
• Physiologic anemia of the neonate

  1. Decrease in hemoglobin

  2. Reduction in the number of RBCs

  3. Decrease in the reticulocyte percentages

  4. Undetectable levels of erythropoietin associated with the transition from the placenta to the lungs as a source of oxygen

  5. Erythropoietic activity increases until it reaches adult levels by age 14 years
• Fetal RBC lifespan

  60 to 70 days in term neonates, 35 to 50 days in premature neonates
• Physiologic anemia is not known to be associated with any abnormalities in the infant
• Hemoglobin levels of premature infants are typically 1 g/dL or more below the values of full-term infants
• Very low-birth-weight infants show a progressive decline in hemoglobin, RBC count, mean cell volume (MCV), mean cell hemoglobin (MCH), and mean cell hemoglobin concentration (MCHC) and have a slower recovery than other preterm and term infants
• Hematocrit


  Average capillary hematocrit at birth for healthy full-term infants is 61%
• Newborns with increased hematocrits, especially values greater than 65%, experience hyperviscosity of the blood
• Hematocrit changes

  1. Increases approximately 5% during the first 48 postnatal hours

  2. Slow linear decline to 46% to 62% at 2 weeks

  3. 32% to 40% between the second and fourth months

  4. Adult values of 47% for males and 42% for females are achieved during adolescence
• Very low-birth-weight preterm infants are often anemic at birth and many require transfusions or erythropoietin injections or both
• Mean cell volume (MCV)

  Erythrocytes of newborn infants are markedly macrocytic at birth, average MCV is 119 ± 9.4 fL, decreases to 90 ± 12 fL in 3 to 4 months
• A newborn with an MCV of less than 94 fL should be evaluated for a-thalassemia or iron deficiency
• Mean cell hemoglobin (MCH)

  30 to 42 pg in healthy neonates, 27 to 41 pg in premature infants
• Mean cell hemoglobin concentration (MCHC)

  Approximately 33 g/dL for full-term infants, premature infants, and adults
• Red blood cell distribution width (RDW)

  Elevated in newborns, reference interval of 14.2% to 17.8% the first 30 days of life, gradually decreases and reaches adult reference interval by 6 months of age
• Iron deficiency anemia


  Most common pediatric hematologic disorder and the most common cause of anemia in childhood