Polycythemia is an abnormally high concentration of red blood cells.

• This disorder may result from postmaturity (see see Problems in Newborns: Postmaturity), diabetes in the mother, or a low oxygen level in the fetal blood.
• A high concentration of red blood cells makes the blood thick (hyperviscosity) and may slow blood flow through small blood vessels.
• Most affected newborns do not have symptoms but occasionally have a ruddy or dusky color, are sluggish (lethargic), feed poorly, and very rarely may have seizures.
• The diagnosis is inferred from a test that measures the content of red blood cells in the blood.
• Usually no treatment is needed except to maintain normal hydration.
• When the newborn has symptoms, treatment with a partial exchange transfusion may be given to reduce the red blood cell concentration.

A markedly increased concentration of red blood cells may result in the blood being too thick, which slows the flow of blood through small blood vessels and interferes with the delivery of oxygen to tissues. A newborn who is born postmaturely or whose mother has diabetes, has severe high blood pressure, smokes, or lives at a high altitude is more likely to have polycythemia. Polycythemia may also result if the newborn receives too much blood from the placenta at birth, as may occur if the newborn is held below the level of the placenta for a time before the umbilical cord is clamped. Other causes include a low oxygen level in the blood (hypoxia), maternal diabetes, growth restriction in the womb, or a large transfusion of blood from one twin to another (twin-to-twin transfusion).

A newborn with severe polycythemia has a very ruddy or dusky color, is lethargic, feeds poorly, and may have seizures. If the newborn has such symptoms, and a blood test indicates too many red blood cells (high hematocrit), some of the newborn's blood is removed and replaced with an equal volume of saline solution, thus diluting the remaining red blood cells and correcting the polycythemia.

Last full review/revision February 2009 by Arthur E. Kopelman, MD