EXAM #2: PEDIATRIC CBC

Question 1

What is a CBC?

Answer 1

Complete Blood Count

Question 2

What are the components of a CBC?

Answer 2

• WBC count
• WBC diff.
• RBC count
• Hbg
• Hct
• MCV
• MCH
• MCHC
• RDW
• Platelet count
• Mean platelet volume

Question 3

In the newborn, what is the normal WBC count?

Answer 3

9,000 - 30,000

Question 4

When in life do you have your highest WBC count?

Answer 4

At birth

Question 5

When do you stop worrying about differences in WBC counts between children and adults?

Answer 5

12 years old

Remember, at 12, greater than 12,000 is abnormal.

Question 6

What is more useful in evaluating the neutrophil count: absolute numbers or percentage?

Answer 6

Absolute count

Question 7

What is the normal absolute neutrophil count? How do you calculate it?

Answer 7

10,000 is roughly normal

Take percentage of neutrophils and multiply by the WBC count

Question 8

What is the normal percentage of neutrophils at birth? How does this compare to the adult?

Answer 8

50-60%

- This is less than the adult value of ~60%

Question 9

How do you know if the number of bands cells is worrisome?

Answer 9

I:T ratio

Question 10

How do you determine an I:T ratio?

Answer 10

Immature: Total neutrophils

Question 11

What are the three types of immature neutrophils?

Answer 11

• Bands
• Metamyelocytes
• Myelocytes

Question 12

How do you interpret an I:T ratio?

Answer 12

1) 0-0.15= low suspicion for sepsis
2) 0.15-0.20= intermediate
3) Greater than 0.20= HIGH suspicion for sepsis

Question 13

What is the normal percentage of lymphocytes in the newborn?

Answer 13

30%

Question 14

How are lymphocytes and neutrophils related?

Answer 14

Inversely i.e. one goes up the other goes down

Question 15

How does the newborn Hb compare to adult normal Hb concentrations?

Answer 15

Newborns have much HIGHER concentrations of Hb

Question 16

What are the normal values for Hb in newborns?

Answer 16

14 - 22 g/dL

Question 17

What is the definition of polycythemia in a neonate?

Answer 17

HCT greater than 65 in a VENOUS sample

Note that capillary samples generally run HIGHER than venous*

Question 18

What is the relationship between HCT and Hb?

Answer 18

3:1 ratio

I.e. a Hb of 15 has a HCT of roughly 45

Question 19

What causes polycythemia?

Answer 19

1) Increased fetal EPO
2) Smoking
3) Alcohol
4) Maternal DM
5) Trisomy
6) Erythrocyte transfusion

Question 20

Why is polycythemia concerning?

Answer 20

Hyperviscosity decreases blood flow to the:

• Heart
• Brain
• Lungs
• Intestines

Question 21

What are the clinical features of polycythemia?

Answer 21

1) Poor feeding
2) Ruddy complexion
3) Irritability
4) Tremors
5) Lethargy
6) Respiratory distress

Question 22

How do you treat an asymptomatic neonate with polycythemia? Symptomatic?

Answer 22

Asymptomatic= hydration and observation

Symptomatic= EXCHANGE TRANSFUSION

Question 23

What is an exchange transfusion?

Answer 23

Draw off blood and replace with saline/LR

Note that this is dangerous and done in an ICU

Question 24

What is the normal RBC lifespan in newborns?

Answer 24

80 days

Vs. 120 days in adults*

Question 25

What is the physiologic anemia of infancy?

Answer 25

B/c of the shorter lifespan of the RBC, there is a NORMAL anemia in a 10-12 week old *****9 g/dL in the term baby and 6 g/dL in the premature baby is NORMAL****

Question 26

When do babies get near adult normal values of Hb?

Answer 26

2 years old

Question 27

How do you calculate the normal lower limit of the MCV in children?

Answer 27

70 fL + age in YEARS E.g. 4 y/o= 70 + 4= 74 fL

Question 28

What is the normal upper limit of an MCV in children?

Answer 28

84fL + (0.6 x age in years)

Question 29

What is Polychromatophilia?

Answer 29

Ability of bone marrow to produce reticulocytes in response to RBC loss

Question 30

Is a RC count part of a normal CBC?

Answer 30

NO, you have to order this separate

Question 31

How do the normal platelet counts compare between children and adults?

Answer 31

SAME i.e. 150,000 - 450,000

Question 32

What is Alloimmune Thrombocytopenia?

Answer 32

Transfer of maternal antibody across the placenta can cause maternal "attack" of paternal antigens on the fetal platelets

Question 33

What is the treatment for Alloimmune Thrombocytopenia?

Answer 33

Transfusion of the MOTHERS platelets *****The platelets transfused will contain the MATERNAL antigens*****

Question 34

When does Alloimmune Thrombocytopenia typically present?

Answer 34

3-4 days

Question 35

What is Maternal ITP?

Answer 35

- Maternal ITP i.e. IgG to platelets | - Crosses placenta and causes same in infant

Question 36

How do you tell the difference between Alloimmune Thrombocytopenia and Maternal ITP?

Answer 36

Maternal platelet count - Mom low in ITP - Mom NOT low in Alloimmune

Question 37

How is Maternal ITP treated in the mother and newborn?

Answer 37

IVIG

Question 38

What is a third cause of thrombocytopenia in the neonate?

Answer 38

Sepsis