Hyperviscosity is when blood flow is slowed and blocked because there are too many red blood cells in an infant's blood.

Hyperviscosity results when the hematocrit is over 65 -- that is, the percentage of red blood cells (RBCs) in the infant's blood is greater than 65%. This may result from various conditions that develop before birth, such as hypoxia, inherited diseases, and birth defects.

The excess RBCs blocks the flow of blood 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, jaundice, and more serious problems.

• Very ruddy red complexion
• Feeding problems
• Lethargy
• Seizures

• Bluish skin
• Low blood sugar
• Rapid breathing
• Respiratory distress
• Kidney failure
• Jaundice

• Hematocrit (RBCs/volume)
• Chem-20 to check blood sugar, BUN, creatinine
• Blood gases
• Urinalysis

A percentage of RBCs above 65% may be treated by raising the volume of body fluids or administering exchange transfusions, both of which can prevent the complications of hyperviscosity.

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

• Seizures
• Kidney failure
• Necrotizing enterocolitis
• Decreased fine motor control
• Strokes

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

Newborn infants are routinely monitored for their RBC levels. (The test is called a hematocrit). This enables quick detection of the condition.