10. Hematology

Question 1

Describe mechanism: Anemia (2)

Answer 1

• decreased production (inadequate reticulocyte response) vs. increased destruction or loss (adequate reticulocyte response)
  
  • in the context of anemia, a normal retic count is inappropriate

Question 2

Describe approach to anemia algorithm

Answer 2

Question 3

Describe: Normal Hb Values by Age

Answer 3

Question 4

Describe: Physiologic Anemia (4)

Answer 4

• high Hb (>170 g/L) and reticulocyte count at birth is caused by a hypoxic environment in utero
• after birth, levels start to fall due to shorter fetal RBC lifespan, decreased RBC production (during first 6-8 wk of life, there is virtually no erythropoiesis due to new O2 rich environment), and increasing blood volume secondary to growth
• lowest levels about 100 g/L at 8-12 wk age (earlier and more exaggerated in premature infants); levels rise spontaneously with activation of erythropoiesis
• usually no treatment require

Question 5

Mean corpuscular volume (MCV) in childhood varies with age. What the Rule of thumb?

Answer 5

lower normal limit of MCV = 70 + age (yr) until 80 fL (adult standard)

Question 6

True or false

Ferritin is an acute phase reactant, therefore, normal or high ferritin does not exclude iron deficiency anemia during an infection

Answer 6

True

Question 7

Iron deficiency is ___ in children <6 mo in the absence of blood loss or prematurity

Answer 7

rare

Question 8

Describe: Iron Deficiency Anemia (4)

Answer 8

• most common cause of childhood anemia
• full term infants exhaust iron reserves by 6 mo of age
• premature infants have lower reserves, therefore exhausted by 2-3 mo of age
• common diagnosis between 6 mo-3 yr and 11-17 yr due to periods of rapid growth and increased iron requirements; adolescents also have poor diet and menstrual losses

Question 9

Describe etiology: Iron Deficiency Anemia (6)

Answer 9

• children at risk (premature, LBW, low SES, etc.)
• dietary risk factors: cow’s milk in first year of life
• age >6 mo: <2 servings/d of iron-fortified cereal, red meat, or legumes
• age <12 mo: use of low-iron formula (<10 mg/L), primary diet of cow, goat, or soy milk
• age 1-5 yr: >16-20 oz/d of non-iron fortified milk
• blood loss
  
  • iatrogenic: repeated blood sampling (especially in hospitalized neonates)
  • allergic: cow’s milk protein-induced colitis

Question 10

Describe clinical feature: Iron Deficiency Anemia (8)

Answer 10

• usually asymptomatic until marked anemia
• symptoms may include:
  
  • pallor
  • fatigue
  • pica (eating non-food materials)
  • tachycardia
  • systolic murmur
  • angular cheilitis
  • koilonychia (spoon nails)

Question 11

Describe investigations: Iron Deficiency Anemia (5)

Answer 11

• CBC: low Hb, MCV, and MCH, reticulocyte count normal or high (absolute number low)
• Mentzer index (MCV/RBC) can help distinguish iron deficiency anemia from thalassemia
  
  • ratio <13 suggests thalassemia
  • ratio >13 suggests iron deficiency
• blood smear: hypochromic, microcytic RBCs, pencil shaped cells, poikylocytosis
• iron studies: low ferritin, other (low iron, high total iron binding capacity, high transferrin, low transferrin saturation)
• initial therapy: trial of iron

Question 12

Describe prevention: Iron Deficiency Anemia (5)

Answer 12

• breastfed term infants: begin iron supplementation (1 mg/kg/d) at 4-6 mo, continuing until able to eat ≥2 feeds/d of iron-rich foods
• non-breastfed (<50% of diet) term infants: give iron-fortified formula from birth
• premature infants: give iron supplements from 1 mo through to 1 yr of age
• no cow’s milk until 9-12 mo, early introduction of red meat and iron-rich vegetables: total daily iron should be 11 mg (age 6-12 mo), 7 mg (age 1-3 yr)
• consider screening Hb levels in infants not receiving iron-fortified formula at 9-12 mo, and earlier if other risk factors

Question 13

Describe management: Iron Deficiency Anemia (3)

Answer 13

• encourage diverse, balanced diet, limit homogenized milk to 16-20 oz/d
• oral iron therapy: 4-6 mg/kg/d elemental iron, divided bid to tid, for 3- 6 mo to replenish iron stores
  
  • increased reticulocyte count in 2-3 d (peaks day 5-7)
  • increased hemoglobin in 4-30 d
  • repletion of iron stores in 1-3 mo
  • repeat hemoglobin levels after 1 mo of treatment
• poor response to oral iron therapy: non-adherance, medication intolerance, ongoing blood loss, IBD, celiac disease, incorrect diagnosis

Question 14

Describe complications: Iron Deficiency Anemia (2)

Answer 14

• can cause irreversible effects on development if untreated (behavioural and intellectual deficiencies)
• angular cheilitis, glossitis, koilonychia (spoon nails)

Question 15

Describe: Vitamin K Deficiency (3)

Answer 15

• hemorrhagic disease of the newborn (HDNB) due to relative deficiencies of vitamin K-dependent coagulation factors
  
  • generalized bleeding; GI/intracranial hemorrhage
  • early-onset (in first 24 hours), classic (day 2 to 2 weeks), and late-onset (2 weeks up to 3-6 mo)
• IM injection at birth, can also be given orally (3 doses: at birth, 2-4 wk, 6-8 wk) but infants at higher risk of HDNB
• reason for administration at birth:
  
  • insufficient prenatal storage of vitamin K and human milk contains small amounts of vitamin K
  • risk factors for non-classic presentation: maternal medication (i.e. antiepileptic drugs), chronic malabsorption, no prophylaxis

Question 16

Fill this table: Evaluation of Abnormal Bruising/Bleeding

Answer 16

Question 17

Describe epidemiology: Immune Thrombocytopenic Purpura (3)

Answer 17

• most common cause of thrombocytopenia in childhood
• peak age: 2-6 yr, M=F
• incidence 5:100,000 children per year

Question 18

Describe etiology: Immune Thrombocytopenic Purpura (1)

Answer 18

• caused by autoantibodies that bind to platelet membranes s Fc-receptor mediated splenic uptake s destruction of platelets

Question 19

Describe clinical features: Immune Thrombocytopenic Purpura (7)

Answer 19

• 50% present 1-3 wk after viral illness (e.g. URTI, chicken pox)
• sudden onset of petechiae, purpura, epistaxis in an otherwise well child
• clinically significant bleed in only 3% (severe bleed more likely with platelet count <10) with <0.5% risk of intracranial bleed
• no lymphadenopathy, no hepatosplenomegaly
• labs: thrombocytopenia with normal RBC, WBC
• bone marrow aspirate only if atypical presentation (≥1 cell line abnormal, hepatosplenomegaly)
• differential diagnosis: leukemia, drug-induced thrombocytopenia, HIV, infection (viral), autoimmune (SLE, ALPS)

Question 20

Describe management: Immune Thrombocytopenic Purpura (9)

Answer 20

• observation vs. pharmacologic intervention highly debated; spontaneous recovery in >70% of cases within 3 mo
• involve family in management; shared decision-making
• no or mild bleeding – strongly consider observation
• moderate bleeding (i.e. severe skin manifestations with some mucosal lesions and some troublesome epistaxis or menorrhagia) – IVIG or steroids; if Rh-positive can use anti-D but not first line due to serious adverse effects
• severe (i.e. prolonged epistaxis, GI bleeding or intracranial hemorrhage) - immediate treatment with IV steroids and IVIG; may use transexamic acid as adjunct therapy
• treatment with IVIg or prednisone if mucosal or internal bleeding, platelets <10, or at risk of significant bleeding (surgery, dental procedure, concomitant vasculitis or coagulopathy)
• life-threatening bleed: additional platelet transfusion ± emergency splenectomy
• persistent (>3-12 mo) or chronic (>12 mo): re-evaluate; treat if symptoms persist
• supportive: avoid contact sports and ASA/NSAIDs

Question 21

Extensive bruising in the absence of lab abnormalities: consider what? (1)

Answer 21

child maltreatment