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What is polycythemia?

Polycythemia is a blood disorder occurring when there are too many red blood cells, which carry oxygen from the lungs through the blood stream to the rest of the body. The excess red blood cells cause the blood to increase in volume and thicken, keeping it from flowing easily.

Polycythemia can be divided into two overarching categories:

  • Primary polycythemia, caused by overproduction of red blood cells by the bone marrow due to mutation or biological factor in the body.
  • Secondary polycythemia, which is caused by factors that reduce the amount of oxygen reaching the body's tissues, such as smoking, high altitude, or congenital heart disease. The red blood cells in some patients with secondary polycythemia may carry an abnormal form of hemoglobin that does not release oxygen readily (high-affinity hemoglobin).

There are three forms of primary polycythemia:

  • polycythemia vera or primary bone marrow polycythemia, an adult disease of the blood-forming hematopoietic stem cells
  • primary familial and congenital polycythemia, caused by genetic abnormalities or inappropriate levels of a hormone called erythropoietin (which triggers red blood cell production)
  • newborn polycythemia, which is detected before or at birth and treated in a neonatal intensive care unit

Polycythemia | Symptoms & Causes

What are the symptoms of polycythemia?

Infants and children with polycythemia often have no visible symptoms. When they do appear, the most common symptoms include:

  • deep reddish-purple coloring
  • poor feeding
  • tiredness or fatigue
  • shortness of breath or breathing difficulty
  • low blood sugar
  • headache
  • dizziness
  • itchiness, especially following a warm bath or shower
  • numbness, tingling, burning, or weakness in your hands, feet, arms, or legs

What causes polycythemia?

Polycythemia may be caused by an increase in a baby’s red cell production due to:

  • chronically lowered oxygen levels
  • some chromosomal abnormalities

Or it can be the result of extra blood cells entering the baby's circulation due to:

  • delay in clamping the umbilical cord after delivery
  • twin-twin transfusion

Polycythemia is rare. Some babies may be at increased risk, including those born:

  • at high altitudes (greater demand for blood to carry oxygen)
  • after 42 weeks gestation
  • small for gestational age or with intrauterine growth restriction (poor growth of the baby while in the womb)
  • identical twins, who share a placenta and develop twin-twin transfusion syndrome
  • to diabetic mothers
  • with chromosomal abnormalities, including trisomy 18 and 13, and trisomy 21 (Down syndrome)

Polycythemia | Diagnosis & Treatments

How is polycythemia diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for polycythemia may include:

  • high red blood cell counts or hemoglobin levels
  • genetic tests to determine what is causing increased red blood cell production

After all tests are completed, doctors will be able to outline the best treatment options.

How is childhood polycythemia treated?

Treatments for polycythemia can include:

  • phlebotomy (withdrawal of blood through the veins)
  • medication such as hydroxyurea to reduce blood cells
  • low-dose aspirin

With secondary polycythemia, treatment usually focuses on the underlying cause.

How we care for polycythemia

Children with polycythemia are treated at the Blood Disorders Center at Dana-Farber/Boston Children's Cancer and Blood Disorders Center, where children and young adults receive care from some of the world’s most experienced hematologists with deep experience in the conditions they treat.

Polycythemia | Research & Innovation

Our areas of research for polycythemia

New medications for adult polycythemia vera are currently in development. The results of these efforts, as well as of studies of the biology of adult polycythemia vera, may one day benefit children with other forms of polycythemia.

Clinical trials

For many children with rare or hard-to-treat conditions, clinical trials provide new options. Search our clinical trials database. If you’re not sure which clinical trials might be right for your child, email us at We can help you navigate your options.

Polycythemia | Programs & Services