Neonatal Polycythemia

Neonatal polycythemia is a hematocrit (HCT) that is 2 standard deviations above the average values for gestation and postnatal age. Neonatal polycythemia can develop from increased fetal hematopoiesis (secondary to placental insufficiency, maternal endocrinopathies, genetic disorders, etc.) or passive erythrocyte transfusion (placental-, feto-, or maternal-fetal transfusion). Patients may be asymptomatic or present with plethora, cardiorespiratory distress, and other symptoms. Continuous monitoring of vital signs and metabolic derangements is important. Treatment includes partial exchange transfusion.

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Overview

Definitions

  • 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

Epidemiology

  •  1%2% of children born at sea level 
  •  5% of children born at high altitudes

Etiology

  • Increased fetal erythropoiesis
    • Placental insufficiency
      • Preeclampsia
      • Maternal hypertension
      • Chronic or recurrent placental abruption
      • Maternal cyanotic heart or severe pulmonary disease
      • Postdate pregnancy
      • Maternal smoking
      • Mother residing at a high altitude
    • Endocrinopathies
      • 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
  • 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

Pathophysiology

  • 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.
Red blood cells stacking

Blood cells on a drying slide flow in rouleau stacks

Image: “Rouleau stacking” by Rozzychan. License: CC BY 4.0

Clinical Presentation

  • 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
    • Seizures
    • 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:
    • Oliguria
    • Hematuria
    • Priapism

Diagnosis and Management

Laboratory studies

  • 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:
    • Thrombocytopenia 
    • Hypoglycemia
    • Hyperbilirubinemia 
    • Hypocalcemia
    • Hypoxia and acidosis in arterial blood gas

Imaging studies

  • 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

Management

  • 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.

References

  1. 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
  2. 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
  3. 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
  4. 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

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