Jaundice (cont.)
What is neonatal jaundice (jaundice in newborn infants)?
Neonatal jaundice is jaundice that begins within the first few days after birth.
(Jaundice that is present at the time of birth suggests a more serious cause of
the jaundice.) In fact, bilirubin levels in the blood become elevated in almost
all infants during the first few days following birth, and jaundice occurs in
more than half. For all but a few infants, the elevation and jaundice represents
a normal physiological phenomenon and does not cause problems.
The cause of normal, physiological jaundice is well understood. During life in
the uterus, the red blood cells of the fetus contain a type of hemoglobin that
is different than the hemoglobin that is present after birth. When an infant is
born, the infant's body begins to rapidly destroy the red blood cells containing
the fetal-type hemoglobin and replaces them with red blood cells containing the
adult-type hemoglobin. This floods the liver with bilirubin derived from the
fetal hemoglobin from the destroyed red blood cells. The liver in a newborn
infant is not mature, and its ability to process and eliminate bilirubin is
limited. As a result of both the influx of large amounts of bilirubin and the
immaturity of the liver, bilirubin accumulates in the blood. Within two or three
weeks, the destruction of red blood cells ends, the liver matures, and the
bilirubin levels return to normal.
There is another uncommon syndrome associated with neonatal jaundice, referred
to as breast-milk or breast feeding jaundice. In this syndrome, jaundice appears
to be caused by or at least accentuated by breast feeding. Although the cause of
this type of jaundice is unknown, it has been hypothesized that there is
something in breast milk that reduces the ability of the liver to process and
eliminate bilirubin. With breast-milk jaundice, the bilirubin levels rise and
reach peak levels in approximately two weeks, remain elevated for a week or so,
and then decline to normal over several weeks or months. This timing of the
elevation in bilirubin and jaundice is different than normal physiological
jaundice described previously and allows the two causes of jaundice to be
differentiated. The real importance of the more prolonged jaundice associate
with breast-milk jaundice is that it raises the possibility that there is a more
serious cause for the jaundice that needs to be sought, for example, biliary
atresia (destruction of the bile ducts). Breast-milk jaundice alone usually does
not cause problems for the infant.
Physiologic jaundice and breast-milk jaundice usually do not cause problems for
the infant; however, there is a concern that high or prolonged elevations in
levels of unconjugated bilirubin (the type of bilirubin that is not attached to
glucuronic acid and the main type of bilirubin that is present in physiologic
and breast-milk jaundice) will cause neurologic damage to the infant. Therefore,
when unconjugated bilirubin levels are high or prolonged, treatment usually is
started to lower the levels of bilirubin. Treatment may be started earlier in
infants who are born prematurely since their livers take longer to mature, and
the risk of higher and more prolonged elevations of bilirubin is greater.
Treatment involves phototherapy with artificial or natural sunlight and, if
phototherapy is not successful, exchange transfusion in which the infant's blood
is exchanged for normal blood from blood donors.
The benign nature of physiologic and breast-milk allergy need to be
distinguished from hemolytic disease of the newborn, a much more serious, even
life-threatening cause of jaundice in newborns that is due to blood group
incompatibilities between mother and fetus, for example Rh incompatibility. The
incompatibility results in an attack by the mother's antibodies on the babies
red blood cells leading to hemolysis. Fortunately, because of modern management
of pregnancy, this cause of jaundice is rare.
Next: How is the cause of jaundice diagnosed? »
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