1. Approach to the newborn with thrombocytopenia
Dr. Lourdes Asiain
Nov 2004

2. Objectives Define mild, moderate and severe thrombocytopenia
List most common causes for the condition
List dysmorphic features assoc with Thrombocytopenia
Description and management of neonatal alloimmune thrombocytopenia

3. Thrombocytopenia: Definition
Mild
100,000 to 150,000
Moderate
50,000 to 99,000
Severe
Less than 50,000

4. Thrombocytopenia: Epidemiology
Up to 25 % of infants admitted to NICU have the condition.
Mild asymptomatic thrombocytopenia occurs in 1% healthy term infants
Severe thrombocytopenia in term infants rare

5. Thrombocytopenia Thrombocytopenia Increased platelet consumption
Impaired
Megakaryopoiesis
Thrombocytopenia

6. Thrombocytopenia: assesment
Term or preterm?
Other medical conditions
Are there features suggestive of congenital infection?
Congenital anomalies/dysmorphism

7. Differential Diagnosis
Sick Neonates, Preterm infants, other medical complications.
Hypoxia and acidosis after birth
Chronic hypoxia from placental insufficiency
Hypothermia
Pre-eclampsia
Sepsis
Congenital viral infections (CMV, rubella)
DIC
NEC
Thrombosis
Exchange transfusions

8. Differential diagnosis
Neonates with physical abnormalities/dysmorphism
Thrombocytopenia with absent radius Synd
Fanconi anemia
Chromosomal disorders (13,18,21, Turner)
Kasabach-Merritt Syndrome

9. Differential diagnosis
Healthy-appearing infant
Occult infection
Maternal autoimmune thrombocytopenia
Neonatal alloimmun thrombocytopeni
Amegakaryocytic thrombocytopenia
Hereditary macrothrombocytopenia
Wiskott-Aldrich Sydrome

10. Common causes Pre-eclampsia
Magnitude usually correlates with severity of HTN
Often have associated neutropenia
Nadir at 3-4 days of life, recovering to normal levels by day 7-10
Rarely severe thrombocytopenia
Possible etiology is disruption of hematopoietic progenitor cell commitment to megakaryopoiesis
Assoc conditions from prematurity may exacerbate condition

11. Common causes Bacterial Sepsis
Several mechanisms that include endothelial damage, immune mediated destruction, platelet aggregation and decreased platelet production.

12. Common causes Viral infections
Viral neuraminidase causes sialic acid loss from platelet membranes
Intravascular platelet aggregation
Congenital infections + Splenomegaly

13. Assoc with Physical abnormalities or dysmorphism
TAR Syndrome
Autosomic recessive
Severe thrombocytopenia and skeletal abnormalities
Can be associated with congenital heart disease
Platelet nadir during first week generally improve by 1-3 years of age.

14. TAR Syndrome

15. Anomalies/Dysmorphism
Fanconi anemia
Aplastic anemia
Thumb anomalies
Anomalies of GU system

16. Abnormalities/Dysmorphism
Kasabach-Merrit Syndrome
Hemangioma
Coagulation is activated locally and platelets are sequestered in the vascular malformation
May not be apparent

17. Maternal autoimmune Thrombocytopenia
ITP, autoimmune diseases
Maternal antibodies vs. platelet antigens
Glycoprotein IIb/IIIa and Ib/IX
Antibodies cross placenta and bind to these antigens on fetal platelets.
Determine the mother’s platelet count

18. Neonatal alloimmune thrombocytopenia
A mother lacks a platelet antogen that her fetus inherited from father.
Maternal IgG vs “foreign” antigen on fetal platelets cross the placenta and destroy them.
Most common platelet antigen HPA-1a

19. Management of immune mediated Thrombocytopenia
IVIG
In cases of severe thrombocytopenia or clinical bleeding
1gram/Kg
In cases of NAIT Head US and platelet transfusion with platelets that are free on HPA1 antigen.

20. Less common etiologies
Congenital amegakarocitic thrombocytopenia (AR)
Heredetary macrothrmbocytopenias (AD)
Wiskott Aldrich Syndrome (WAS protein X)
Immunedefiency
Eczema
Thrombocytopenia

21. Conclusions
Thrombocytopenia is often encountered in newborns, specially sick preterm infants
Initial assessment should consider gestational age, co-morbid conditions, congenital-physical anomalies and dysmorphism.

22. Thank You
References
NeoReviews.org: Approach to the Newborn who has thrombocytopenia. Vol
Curr opinion Obst Gynecol: Platelet disorders in pregnancy. 2001;13:
Avery’s Diseases of the Newborn. Taesch et Ballard.