Snapshot A 2-day-old newborn presents with cyanosis and irritability. His mother had gestational diabetes, which resulted in a difficult delivery due to the baby’s large size. Delivery was further complicated by delayed clamping of the umbilical cord. On physical exam, the patient has plethora and ruddiness of his face. Heelstick hematocrit was found to be 71%. Venous sampling of hematocrit was found to be 68%. Introduction Venoushematocrit exceeding normal values for gestational and postnatal age typically hematocrit > 65% Most babies are asymptomatic Distinct from adult polycythemia vera, a myeloproliferative neoplastic disorder EPIDEMIOLOGY Risk factors delayed clamping of umbilical cord (most common) ↑ transfer of placental blood to infant twin-to-twin transfusion placental insufficiency maternal diabetes maternal hypoxemia macrosomia maternal hypertension Hyperviscosity thought to play a role in symptoms, if any Presentation Majority are asymptomatic Symptoms/physical exam GI upset poor feeding vomiting hypoglycemia cyanosis/apnea plethora respiratory distress lethargy studies Venous hematocrit > 65% Glucose for hypoglycemia Bilirubin level ↑ RBC can lead to hyperbilirubinemia Observe closely for neurologic and cardiovascularsymptoms may have underlying pathologic causes of polycythemia Differential Other causes of polycythemia vera hypoxemia Treatment Asymptomatic supportive care monitor bilirubin and glucose Symptomatic IV hydration with glucose many have hypoglycemia partial exchange transfusion reduces Hct without hypovolemia may not improve outcomes used only if symptoms worsen Complications Hypoglycemia Prognosis Unclear effect on long-term outcome