Hyperviscosity in the newborn is defined as increased resistance to blood flow as a result of an abnormally high hematocrit (percentage of red blood cells in the whole blood) level.

Alternative Names

Neonatal polycythemia

Causes, incidence, and risk factors

Hyperviscosity results when the percentage of red blood cells (RBCs) in the infant's blood is greater than 65%. High hematocrits may result from various intrauterine conditions such as hypoxia , inherited diseases, and congenital abnormalities. The high percentage of RBCs causes blockage of blood flow in the smallest capillaries. This leads to tissue death from lack of oxygen. This blocked blood flow can affect all organs such as the kidneys, lungs, and brain. Infants with hyperviscosity may develop feeding problems, cyanosis , low blood sugar , elevated bilirubin ( jaundice ), and other more serious findings.

Signs and tests

Treatment

Expectations (prognosis)

The outcome is good in infants with mild hyperviscosity and in those with severe hyperviscosity that receive treatment.

Complications

Calling your health care provider

Call your health care provider if this condition is diagnosed at birth and you have additional questions.

Prevention

Newborn infants are routinely monitored for the hematocrit level, enabling quick detection of the condition.