- Neonatal polycythemia (absolute polycythemia): increased erythrocyte mass defined as hematocrit (HCT) > 65% or hemoglobin (Hb) > 22 g/dL
- Hemoconcentration (relative polycythemia): a decrease in plasma volume resulting in an increased concentration of erythrocytes
- 1%–2% of children born at sea level
- 5% of children born at high altitudes
- Increased fetal erythropoiesis
- Placental insufficiency
- Maternal hypertension
- Chronic or recurrent placental abruption
- Maternal cyanotic heart or severe pulmonary disease
- Postdate pregnancy
- Maternal smoking
- Mother residing at a high altitude
- Poorly controlled maternal diabetes
- Congenital thyrotoxicosis
- Genetic disorders
- Trisomies 13, 18, 21
- Beckwith-Weidemann syndrome
- Adrenal hyperplasia
- Perinatal asphyxia
- Intrauterine growth restriction
- Intrauterine chronic hypoxia
- Placental insufficiency
- Passive erythrocyte transfusion
- Placental-fetal transfusion (delayed cord clamping, newborn held below mother’s level before cord clamping)
- Feto-fetal transfusion (twin-twin transfusion syndrome)
- Mother-fetal hemorrhage
- Blood viscosity increases with increased HCT.
- Hyperviscosity increases resistance to blood flow, especially in the microcirculation.
- Decreased blood flow increases risk for thrombosis and hypoperfusion.
- Lung hypoperfusion causes further tissue hypoxia.
- The majority of cases are asymptomatic.
- If present, symptoms usually appear by 2 hours after birth.
- Most characteristic findings: plethora and ruddiness
- Neurologic manifestations:
- Poor feeding and lethargy
- Irritability, jitteriness, and tremor
- Cerebrovascular accidents
- Cardiopulmonary manifestations:
- Respiratory distress and tachypnea
- Cyanosis and apnea
- Gastrointestinal manifestations:
- Necrotizing enterocolitis with feeding intolerance, abdominal distension and tenderness, rectorrhagia, bradycardia, and apnea
- Genitourinary manifestations:
Diagnosis and Management
- Diagnosis is confirmed with a complete blood count showing HCT > 65% or Hb > 22 mg/dL (capillary values must be confirmed by venous values).
- Other common findings:
- Hypoxia and acidosis in arterial blood gas
- May be required to exclude differential diagnoses or complications
- Cranial ultrasound, computed tomography (CT) scan, or magnetic resonance imaging (MRI) to rule out cerebrovascular accident (CVA) including intracranial hemorrhage
- Echocardiography to rule out cardiopulmonary disorders
- Chest X-ray to rule out transient tachypnea of the newborn, respiratory distress syndrome, pneumonia
- Abdominal X-ray or CT scan for signs of necrotizing enterocolitis
- Careful monitoring for vital signs, hypoglycemia, hypoxia, electrolyte abnormalities, hyperbilirubinemia, and urine output
- Mainstay of treatment is partial exchange transfusion (PET):
- PET involves slowly removing blood and infusing normal saline.
- Asymptomatic patients with HCT > 75% may benefit from PET.
- Symptomatic patients with HCT 60%–65%: consider alternative diagnoses
- Symptomatic patients with HCT > 65%: consider PET
- It is unclear whether polycythemia or PET have long-term health consequences.
- Brandow, A. M., & Camitta, B. M. (2020). Polycythemia. In R. M. Kliegman MD, J. W. St Geme MD, N. J. Blum MD, Shah, Samir S., MD, MSCE, Tasker, Robert C., MBBS, MD & Wilson, Karen M., MD, MPH (Eds.), Nelson textbook of pediatrics (pp. 256-2567.e1). https://www.clinicalkey.es/#!/content/3-s2.0-B9780323529501004934
- Watchko, J. F., M.D. (2015). Common hematologic problems in the newborn nursery. Pediatric Clinics of North America, 62(2), 509-524. doi:http://dx.doi.org/10.1016/j.pcl.2014.11.011
- Neonatal polycythemia. UpToDate. Retrieved September 23, 2020, from https://www.uptodate.com/contents/neonatal-polycythemia?search=neonatal%20polycythemia&source=search_result&selectedTitle=1~13&usage_type=default&display_rank=1#H25988283
- Kremyanskaya, M., Najfeld, V., Mascarenhas, J., & Hoffman, R. (2018). The polycythemias. In R. Hoffman MD, E. J. Benz MD, L. E. Silberstein MD, Heslop, Helen E., MD, DSc (Hon), J. I. Weitz MD, J. Anastasi MD. Hematology: Basic principles and practice (pp. 1071-1105). https://www.clinicalkey.es/#!/content/3-s2.0-B9780323357623000688