Pediatric CBC

Question 1

what blood components are included in the CBC?

Answer 1

RBCs, WBCs, platelets

Question 2

what is the accepted range of WBCs for newborns?

Answer 2

9000 - 30,000

Question 3

neutrophils account for what % of WBCs at birth?

Answer 3

50-60%

Question 4

when is the number of absolute bands highest?

Answer 4

first 2 days of life

Question 5

how do you calculate the I:T ratio?

Answer 5

1. sum of immature forms in numerator

2. total neutrophil forms in denominator

Question 6

what I:T ratio signifies a high suspicion for sepsis?

Answer 6

greater than 0.20

Question 7

how do Hb and Hct levels at birth compare to kids and adults?

Answer 7

higher

Question 8

what is the normal ratio of Hct to Hb?

Answer 8

3:1

Question 9

what is polycythemia? what is the diagnostic value associated with it?

Answer 9

1. pathologic increase in RBC mass

2. venous Hct greater than 65% in neonatal period

Question 10

how does capillary Hct compare to venous?

Answer 10

runs slightly higher

Question 11

why do capillary Hct samples run higher than venous?

Answer 11

manual pushing from heel stick results in an increased proportion of cells to be obtained compared to fluid volume

Question 12

what are the clinical outcomes of venous polycythemia greater than 65%?

Answer 12

hyperviscosity

Question 13

what is the treatment for symptomatic and asyomptomatic polylcythemia?

Answer 13

1. symptomatic - exchange transfusion

2. asymptomatic - hydrate and monitor

Question 14

how is polycythemia defined after the neonatal period?

Answer 14

Hb and Hct that is two standard deviations above the mean

Question 15

what is the RBC lifespan in the newborn?

Answer 15

80 days

Question 16

what is the cause of physiologic anemia of infancy?

Answer 16

fall in Hb around 2 months of age due to

1. decreased RBC lifespan
2. decreased erythropoiesis

Question 17

how do you calculate the lower limit of MCV in children under 10 years of age?

Answer 17

70 fL plus age in years

Question 18

how do you calculate the upper limit of MCV (after 6 months of age)?

Answer 18

84 fL plus (0.6 x age in years)

Question 19

what is the normal range for platelets throughout life?

Answer 19

150,000 - 450,000

Question 20

what are the three causes of thrombocytopenia in the newborn?

Answer 20

1. alloimmune
2. ITP
3. sepsis

Question 21

what are the mechanism for sepsis induced thrombocytopenia in the newborn?

Answer 21

1. Transient hypoproliferative state in bone marrow

2. Platelet aggregation from bacterial products

Question 22

what is the mechanism for ITP induced thrombocytopenia in the newborn?

Answer 22

autoimmune - mother has Abs that react with platelets - also react with baby’s platelets

Question 23

what is the mechanism for alloimmune thrombocytopenia?

Answer 23

1. transfer of Abs across the placenta

2. coated platelets are destroyed

Question 24

what is the treatment for alloimmune thrombocytopenia? why?

Answer 24

1. mother’s platelets

2. Abs would not react to these