What is polycythemia?

Polycythemia is a condition in which there are too many red blood cells in the blood circulation. It is the opposite of anemia, which results from too few red blood cells in the blood circulation. Polycythemia is also called plethora when it causes a ruddy complexion.

What causes polycythemia?

Polycythemia may be caused by the following:

  • Increased red blood cell production:

    • A fetus with chronically lowered oxygen levels responds by producing extra red blood cells.

    • Some chromosomal abnormalities may cause increased red blood cell production.

  • Extra blood cells enter the baby's circulation from another source:

    • A delay in clamping the umbilical cord after delivery results in blood from the placenta entering the baby's circulation.

    • Twin-to-twin transfusion, which is when the shared placenta of the two babies has a connecting circulation and blood flows from one baby to the other, may result in polycythemia.

Who is affected by polycythemia?

Polycythemia may occur with many different conditions. Some of the babies affected by polycythemia include:

  • Those born or living at high altitudes because of the greater demand for blood to carry oxygen

  • Those born after 42 weeks gestation

  • Small for gestational age/intrauterine growth restriction

  • The identical twin who is the recipient in twin-to-twin transfusion

  • Infants of diabetic mothers

  • Those with chromosomal abnormalities including trisomies 13, 18, and 21 (Down syndrome)

Why is polycythemia a concern?

Mild polycythemia may not cause problems. However, too many red blood cells can increase the blood volume or thicken the blood, making it harder to circulate through the blood system and to the organs. Babies can have difficulty breathing and their heart and blood vessels cannot compensate for the extra amount of blood. As the large numbers of cells begin to break down, a substance called bilirubin is produced. Increased bilirubin levels, called hyperbilirubinemia, can cause jaundice, a yellowing of the skin, eyes, and mucous membranes. Seizures can also occur with polycythemia.

What are the symptoms of polycythemia?

Many babies with polycythemia have no visible symptoms of the condition. The following are the most common symptoms of polycythemia. However, each baby may experience symptoms differently. Symptoms may include:

  • Deep reddish-purple coloring

  • Poor feeding

  • Lethargy

  • Rapid breathing or respiratory distress

  • Jaundice (yellowing of the skin, eyes, and mucous membranes)

  • Low blood sugar

The symptoms of polycythemia may resemble other conditions or medical problems. Always consult your baby's doctor for a diagnosis.

How is polycythemia diagnosed?

Laboratory tests show a high hematocrit (red blood cell count) when polycythemia is present. A high hemoglobin (protein in the blood that carries oxygen) level may also help diagnose polycythemia. Your child may also be tested for a genetic mutation in the janus kinase 2 (JAK2) gene that occurs in primary polycythemia, but not in secondary polycythemia. Primary polycythemia is rarely found in children. 

Treatment for polycythemia

Specific treatment for polycythemia will be determined by your baby's doctor based on:

  • Your baby's gestational age, overall health, and medical history

  • Extent of the disease

  • Your baby's tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the disease

  • Your opinion or preference

Treatment may include:

  • Removing some of the blood volume, thus reducing the number of red blood cells.

  • Replacement of the withdrawn blood with fluids (to help dilute the red blood cell concentration).

  • Partial exchange transfusion (slowly removing and replacing a large portion of the baby's blood volume).

These treatments are performed through a vein or artery, often the umbilical blood vessels.