Lecture 1 Pediatric Hematology

Question 1

What are the 3 stages of blood cell embryonic development?

Answer 1

Blood cell embryonic development from stem cells is in 3 stages:
1. Mesoblastic (yolk sac)
2. Hepatic (liver)
3. Myeloid (bone marrow)

Question 2

Does extramedullary hematopoiesis occur in a full term infant?

Answer 2

No, if it did that would be abnormal.

Question 3

What are the three development stages for pediatric hematology?

Answer 3

Pediatric - development stages:
1. Neonatal period-first 4 weeks of life.
2. Infancy-first year of life.
3. Childhood age 1 to puberty (age 8 to 12 years)

Question 4

What is a full term baby defined as? Premature? Post-term?

Answer 4

Full term defined as 37 to 42 weeks
Infants before 37 wks premature
Infants after 42 wks considered postterm

Hematology values for full term babies generally do not apply to preterm infants.

Question 5

How does birth weight in preterm infants affect hematology values (in general)?

Answer 5

Hematology values will also differ comparing low birth weight preterm infants to extremely low birth weight preterm infants (24 to 26 weeks gestation).

Question 6

What are the RBC values in infants like at birth and for the next few weeks?

Answer 6

RBC Values (general)
1. Newborn polycythemia
2. RBC count increases during the first 24 hours of life, plateaus for approx 2 weeks, then slowly declines.

Question 7

Why are infants born with polycythemia and then after 2 weeks the RBC count declines?

Answer 7

1. Newborn polycythemia explained by utero hypoxia and ↑ Hb F.
2. Decreasing RBC count due to ↓ Hb F and ↑ oxygenation from lungs.

Note: Hgb and Hct parallel increases/decreases of RBCs.

Question 8

What is the characteristics of RBC’s of the neonate?

Answer 8

1. RBC’s are macrocytic from first 11 days of gestation until 5 days postnatal.
2. NRBCs frequently observed on first day of life, disappear in 3-5 days.
3. RDW (anisocytosis) elevated in newborns (range is 14.2-19.2%).

Question 9

What does it mean if NRBCs persist in the blood greater than 5 days after birth?

Answer 9

If NRBCs > 5 days suggests hemolysis, hypoxic stress, infection.

Question 10

What kind of RBC morphology can be expected in the neonate’s peripheral blood?

Answer 10

Neonate’s peripheral blood:
1. Increased # of stomatocytes.
2. Increased # of spherocytes.
3. Increased # of target cells and acanthocytes.

Question 11

Why is there increased numbers of target cells and acanthocytes in the neonate?

Answer 11

increased numbers of target cells and acanthocytes if liver not yet functioning properly due to increased plasma lipids.

Question 12

Describe new born reticulocyte count.

Answer 12

At newborn stage:
Reticulocytosis increased in utero and at birth. Persists 3 days after birth and then declines in days 4-7.

12 weeks gestation –> 90% retics
6 months gestation –> 15% retics
Birth –> 4-6% retics

Question 13

What is the % hemoglobin F content in the fetus and newborn at birth?

Answer 13

30 weeks gestation –> 90-95% HbF.
Birth –> 70-80% HbF
6 months of age –> 2-3% HbF

Question 14

What are normal and abnormal levels of hemoglobin at birth?

Answer 14

Normal Hgb at birth 165 to 215 g/L
Abnormal < 140g/L

Abnormal requires follow-up investigation for conditions such as microcytic anemia (Iron deficiency or Thalassemia, etc.)

Question 15

What are the physiological decreases of the neonate in general?

Answer 15

The following values all decrease:
Hgb,
Hct,
RBC Count,
Retculocytosis,
Undetectable levels of erythropoietin.

Question 16

Why do they think Hgb values decrease in the first 5-8 weeks of life?

Answer 16

Because of decreasing HbF and transition from placenta to lungs as a source of oxygen.

Question 17

What happens to the life span of the RBC’s in a newborn?

Answer 17

Life span of RBCs are shortened in a newborn 60-70 days.

Plays a role in decreasing Hgb, RBC and Hct.
Baby does not require such high values, breathing on its own.

Question 18

What is the average MCV for a full term infant?

Answer 18

Average MCV for a full term infant:
110 +/- 15 fL

Then decreases sharply in first 24 hours of life.

Question 19

When does MCV become normal in a newborn? What is the normal value?

Answer 19

MCV becomes normal around 3-4 months.

Normal value is 90 + 12 fL.

Question 20

Describe the neutrophil count from birth till 4 years of age?

Answer 20

Neutrophil excess segmented neutrophils and bands with occ’l metamyelocytes.

12 hours of life –> Absolute neutrophil count (ANC) rises
1 month to 1 year –> ANC decreases
4 years of age –> ANC stabilizes

Question 21

How does WBC count vary at birth?

Answer 21

Leukocytosis at birth.
Wide range of normal values making finding a normal range difficult.

Question 22

How do lymphocytes vary from birth to childhood?

Answer 22

Lymphocytes are high at birth and generally stay high compared to adult values throughout newborn infant and childhood stages.

Birth –> 30%
4-6 m –> 60%
4 years –> 50%
6 years –> 40%
8 years –> 30%

Question 23

What WBCs remain relatively constant in number/% from infancy to adulthood?

Answer 23

Eosinophils and Basophils.

Question 24

How does the monocytes count vary from neonate to childhood?

Answer 24

Neonate - higher than adult % of monocytes (mean)
Birth - 6% monocytes
Infancy/Childhood - 5% monocytes avg.
3-5 months - adult levels (2-11%)

Question 25

Describe kiddie lymph morphology.

Answer 25

Kiddie Lymphs* vary in size 10-20 um.
Condensed homogenous chromatin.
Scant/sparse cytoplasm.
May have small, distinct nucleoli.

• differs from normal adult lymph morphology

Question 26

How do platelet counts of the newborn vary from the adult?

Answer 26

Platelet counts of newborns are essentially the same as those of adults.

Newborns 150-400x10^9/L versus
Adults 150-450 x10^9/L.

Question 27

In what way do platelets of a newborn vary in morphology from an adults?

Answer 27

Newborn platelets vary greater in size and shape in comparison to an adult’s platelets.

Higher PDW value, i.e. Platelet Distribution Width.