From the moment a baby is born, a number
of key tests are done to make sure the infant is healthy. Here is an
explanation of the major ones:
Apgar Score
The Apgar score, designed in 1952 by Virginia Apgar, MD, is an objective
method of evaluating a newborn's overall state of health. To arrive at
the score, five characteristics are evaluated-respiratory effort, heart
rate, muscle tone, skin color and reflex irritability (the response of
the baby to a stimulus like suctioning). Each is rated 0, 1 or 2, and
the total score is the sum of these five ratings. The evaluation is
performed twice, at one minute and at five minutes after birth. The one
minute Apgar score assesses how well the newborn tolerated the birthing
process, and the five minute score appraises how well the baby is
adapting to the environment. A score of eight to 10 is normal and
indicates that the newborn is in good condition. A perfect score of 10
is very unusual, since almost all newborns lose a point for blue hands
and feet.
Blood Sugar
Low blood glucose is fairly common in newborns. Extremely low levels are
found in premature infants, babies small for their gestational age, and
infants born to diabetic mothers. In the latter case, increased insulin
in the baby's blood can drive the newborn's blood sugar down to
dangerous levels. Low blood sugar in babies is a medical emergency that
can result in seizures and neurological damage if not treated.
White Blood Count
Bacterial infections in newborns can have devastating results since this
illness appears quickly, often without warning or symptoms. Many times
there is only the history of fever in the mother, the presence of foul
smelling amniotic fluid at delivery, or a nursery nurse who reports that
the infant "just doesn't look right." When an infection is
suspected, a white blood count (done as part of a CBC - complete blood
count) is obtained from a small amount of blood. The total numbers of
white cells are reported along with the different types of white cells
present. Too many immature white cells in proportion to the total number
of white cells may be an early warning sign of an infection. Antibiotics
are often started simply on the basis of the child's history and the
elevation of the white blood count, and continued until blood culture
results are available.
Before discharge, the newborn will be screened for certain birth
defects. While these conditions have no visible effects on the baby,
they can cause severe problems if not detected and treated.
Phenylketonuria
This hereditary enzyme deficiency, usually referred to as, "PKU"
can be devastating if undetected and untreated, since it will result in
mental retardation. This was the nation's first newborn screening test
used to detect a condition that affects one baby in 12,000. Children
with this disorder cannot process a protein called phenylalanine. If
detected, however, it is easily treated with a special formula low in
phenylalanine during infancy and a diet low in phenylalanine during
childhood and perhaps indefinitely.
Thyroid Function
A test to detect congenital hypothyroidism -- underproduction of thyroid
hormones -- is the disorder most commonly identified by routine neonatal
screening. Congenital hypothyroidism affects one baby in 4,000 and
employs the same tiny drop of blood taken from the baby's heel to test
for PKU. If the condition is found, treatment in the form of oral
thyroid hormone is started immediately, and the delayed physical growth
and profound mental retardation that would have developed are prevented.
Galactosemia
About one out of 65,000 newborns is born with an enzyme deficiency that
prevents them from converting galactose, a sugar found in milk, into
glucose. As a result, galactose builds up in the blood resulting in poor
weight gain during infancy. Failure to recognize this problem then
results in cataracts, enlargement of the liver, chronic liver disease
and mental retardation.
Sickle Cell Disease and other Disorders of Hemoglobin
Sickle cell diseases affect about one in 400 American black newborns.
These and other abnormalities of the hemoglobin protein are common in
persons of African, Mediterranean, Asian, Caribbean, and South and
Central American origins as well. Early diagnosis and treatment of these
conditions made possible by newborn screening has drastically reduced
the devastating effects of these blood diseases. Young children with
sickle cell disease are especially prone to certain dangerous bacterial
infections, such as pneumonia and meningitis. Newborn screening allows
the physician to be aware of the rapid onset of bacterial infection and
to begin antibiotic treatment early in the course of the infection.
Sometimes prophylactic antibiotics are instituted.
Congenital Adrenal Hyperplasia
This disorder is discovered in one in 12,000 births. The defect results
from the lack of an enzyme needed by the adrenal gland to make
corticosteroids. In the most severe form of this condition, symptoms
develop shortly after birth due to the loss of salt. Symptoms include
vomiting, dehydration, electrolyte changes and cardiac arrhythmias.
Untreated, this condition can lead to death within days of the infant's
birth. Replacement treatment with the missing hormones, when started
early, will save the baby's life and prevent other complications.
Testing is an individual function of each state and is not uniform
throughout the United States. Infants who go home after only 24 hours
need to be retested within the first three weeks of life since some of
the diseases can be missed when the test is performed too early. In
addition, all newborns should have a pediatrician or family practice
physician designated before discharge to ensure prompt follow-up for any
abnormal results. Fortunately, most newborns whose initial tests are
abnormal have normal results on repeated testing.
