EXAM #2: PEDIATRIC CBC Flashcards
What is a CBC?
Complete Blood Count
What are the components of a CBC?
- WBC count
- WBC diff.
- RBC count
- Hbg
- Hct
- MCV
- MCH
- MCHC
- RDW
- Platelet count
- Mean platelet volume
In the newborn, what is the normal WBC count?
9,000 - 30,000
When in life do you have your highest WBC count?
At birth
When do you stop worrying about differences in WBC counts between children and adults?
12 years old
Remember, at 12, greater than 12,000 is abnormal.
What is more useful in evaluating the neutrophil count: absolute numbers or percentage?
Absolute count
What is the normal absolute neutrophil count? How do you calculate it?
10,000 is roughly normal
Take percentage of neutrophils and multiply by the WBC count
What is the normal percentage of neutrophils at birth? How does this compare to the adult?
50-60%
- This is less than the adult value of ~60%
How do you know if the number of bands cells is worrisome?
I:T ratio
How do you determine an I:T ratio?
Immature: Total neutrophils
What are the three types of immature neutrophils?
- Bands
- Metamyelocytes
- Myelocytes
How do you interpret an I:T ratio?
1) 0-0.15= low suspicion for sepsis
2) 0.15-0.20= intermediate
3) Greater than 0.20= HIGH suspicion for sepsis
What is the normal percentage of lymphocytes in the newborn?
30%
How are lymphocytes and neutrophils related?
Inversely i.e. one goes up the other goes down
How does the newborn Hb compare to adult normal Hb concentrations?
Newborns have much HIGHER concentrations of Hb
What are the normal values for Hb in newborns?
14 - 22 g/dL
What is the definition of polycythemia in a neonate?
HCT greater than 65 in a VENOUS sample
Note that capillary samples generally run HIGHER than venous*
What is the relationship between HCT and Hb?
3:1 ratio
I.e. a Hb of 15 has a HCT of roughly 45
What causes polycythemia?
1) Increased fetal EPO
2) Smoking
3) Alcohol
4) Maternal DM
5) Trisomy
6) Erythrocyte transfusion
Why is polycythemia concerning?
Hyperviscosity decreases blood flow to the:
- Heart
- Brain
- Lungs
- Intestines
What are the clinical features of polycythemia?
1) Poor feeding
2) Ruddy complexion
3) Irritability
4) Tremors
5) Lethargy
6) Respiratory distress
How do you treat an asymptomatic neonate with polycythemia? Symptomatic?
Asymptomatic= hydration and observation
Symptomatic= EXCHANGE TRANSFUSION
What is an exchange transfusion?
Draw off blood and replace with saline/LR
Note that this is dangerous and done in an ICU
What is the normal RBC lifespan in newborns?
80 days
Vs. 120 days in adults*
What is the physiologic anemia of infancy?
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*
When do babies get near adult normal values of Hb?
2 years old
How do you calculate the normal lower limit of the MCV in children?
70 fL + age in YEARS
E.g. 4 y/o= 70 + 4= 74 fL
What is the normal upper limit of an MCV in children?
84fL + (0.6 x age in years)
What is Polychromatophilia?
Ability of bone marrow to produce reticulocytes in response to RBC loss
Is a RC count part of a normal CBC?
NO, you have to order this separate
How do the normal platelet counts compare between children and adults?
SAME i.e. 150,000 - 450,000
What is Alloimmune Thrombocytopenia?
Transfer of maternal antibody across the placenta can cause maternal “attack” of paternal antigens on the fetal platelets
What is the treatment for Alloimmune Thrombocytopenia?
Transfusion of the MOTHERS platelets
The platelets transfused will contain the MATERNAL antigens
When does Alloimmune Thrombocytopenia typically present?
3-4 days
What is Maternal ITP?
- Maternal ITP i.e. IgG to platelets
- Crosses placenta and causes same in infant
How do you tell the difference between Alloimmune Thrombocytopenia and Maternal ITP?
Maternal platelet count
- Mom low in ITP
- Mom NOT low in Alloimmune
How is Maternal ITP treated in the mother and newborn?
IVIG
What is a third cause of thrombocytopenia in the neonate?
Sepsis
