Approach to the newborn with thrombocytopenia

Dr. Lourdes AsiainNov 2004

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

Thrombocytopenia: Definition

Mild 100,000 to 150,000

Moderate 50,000 to 99,000

Severe Less than 50,000

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

Thrombocytopenia

Thrombocytopenia

Increased plateletconsumption

ImpairedMegakaryopoiesis

Thrombocytopenia: assesment

Term or preterm?Other medical conditionsAre there features suggestive of

congenital infection?Congenital anomalies/dysmorphism

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

Differential diagnosis

Neonates with physical abnormalities/dysmorphismThrombocytopenia with absent radius SyndFanconi anemiaChromosomal disorders (13,18,21, Turner)Kasabach-Merritt Syndrome

Differential diagnosis

Healthy-appearing infant Occult infectionMaternal autoimmune thrombocytopeniaNeonatal alloimmun thrombocytopeniAmegakaryocytic thrombocytopeniaHereditary macrothrombocytopeniaWiskott-Aldrich Sydrome

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

Common causes

Bacterial Sepsis

Several mechanisms that include endothelial damage, immune mediated destruction, platelet aggregation and decreased platelet production.

Common causes

Viral infectionsViral neuraminidase causes sialic acid loss

from platelet membranes

Intravascular platelet aggregation

Congenital infections + Splenomegaly

Assoc with Physical abnormalities or dysmorphism

TAR SyndromeAutosomic recessiveSevere thrombocytopenia and skeletal

abnormalities Can be associated with congenital heart

diseasePlatelet nadir during first week generally

improve by 1-3 years of age.

TAR Syndrome

Anomalies/Dysmorphism

Fanconi anemiaAplastic anemia

Thumb anomalies

Anomalies of GU system

Abnormalities/Dysmorphism

Kasabach-Merrit SyndromeHemangiomaCoagulation is activated locally and platelets

are sequestered in the vascular malformation

May not be apparent

Maternal autoimmune Thrombocytopenia

ITP, autoimmune diseasesMaternal 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

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

Management of immune mediated Thrombocytopenia

IVIG In cases of severe thrombocytopenia or

clinical bleeding1gram/Kg In cases of NAIT Head US and platelet

transfusion with platelets that are free on HPA1 antigen.

Less common etiologies

Congenital amegakarocitic thrombocytopenia (AR)

Heredetary macrothrmbocytopenias (AD)

Wiskott Aldrich Syndrome (WAS protein X)

ImmunedefiencyEczemaThrombocytopenia

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.

Thank You

ReferencesNeoReviews.org: Approach to the Newborn

who has thrombocytopenia. Vol.5 2004Curr opinion Obst Gynecol: Platelet

disorders in pregnancy. 2001;13:115-119Avery’s Diseases of the Newborn. Taesch

et Ballard.