Polycythemia - newborn

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Polycythemia can occur when there are too many red blood cells in an infant's blood.

Alternative Names

Neonatal polycythemia; Hyperviscosity - newborn


The percentage of red blood cells (RBCs) in the infant's blood is called the "hematocrit." When this test is greater than 65%, polycythemia is present.

Polycythemia can result from conditions that develop before birth. These may include:

  • Delay in clamping the umbilical cord
  • Diabetes in the baby's birth mother
  • Inherited diseases and genetic problems
  • Too little oxygen reaching body tissues (hypoxia)
  • Twin-twin transfusion syndrome (This occurs when blood moves from one twin to the other.)

The extra RBCs can slow or block the flow of blood in the smallest blood vessels. This is called hyperviscosity. This may lead to tissue death from lack of oxygen. This blocked blood flow can affect all organs, including the kidneys, lungs, and brain.


Symptoms may include:

  • Extreme sleepiness
  • Feeding problems
  • Seizures

Exams and Tests

There may be signs of breathing problems, kidney failure, low blood surgar, or newborn jaundice.

If the baby has symptoms of hyperviscosity, a blood test to count the number of red blood cells will be done. This test is called a hematocrit.

Other tests may include:

  • Blood gases to check oxygen level in the blood
  • Blood sugar (glucose) to check for low blood sugar
  • Blood urea nitrogen (BUN), a substance that forms when protein breaks down
  • Creatinine
  • Urinalysis


The baby will be monitored for complications of hyperviscosity. Intravenous (IV) fluid may be given. A partial volume exchange transfusion is sometimes still done in some cases. However, there is little evidence that this is effective.

Outlook (Prognosis)

The outlook is good for infants with mild hyperviscosity. Good results are also possible in infants who receive treatment for severe hyperviscosity. The outlook will depend largely on the reason for the condition.

Some children may have mild developmental changes. Parents should contact their health care provider if they think their child shows signs of delayed development.

Possible Complications

Complications may include:

  • Death of intestinal tissue (necrotizing enterocolitis)
  • Decreased fine motor control
  • Kidney failure
  • Seizures
  • Strokes


Mathews DC, Glader B. Erythrocyte disorders of infancy. In: Gleason CA, Devaskar SU, eds. Avery's Diseases of the Newborn. 9th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 77.

Yaser D, Luchtman-Jones L. Hematologic and oncologic problems in the fetus and neonate. In: Martin RJ, Fanaroff AA, eds. Fanaroff and Martin's Neonatal-Perinatal Medicine. 10th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 88.

Version Info

  • Last reviewed on 4/27/2015
  • Kimberly G Lee, MD, MSc, IBCLC, Associate Professor of Pediatrics, Division of Neonatology, Medical University of South Carolina, Charleston, SC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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