Newborn screening is the practice of testing
every newborn for certain harmful or potentially fatal disorders that are
not otherwise apparent at
birth. Many of these are metabolic disorders, often called
"inborn errors of metabolism," which interfere with the body's use of
nutrients to maintain healthy tissues and produce energy. Other disorders
that may be detected through screening include problems with hormones,
vitamin levels, or the blood.
In general, metabolic and other
can hinder an infant's normal physical and mental development in a variety
of ways. And parents can pass along the gene for a certain disorder
without even knowing that they're carriers.
With a simple blood test, doctors often can tell
whether newborns have certain conditions that could eventually cause
problems. Even though these conditions are considered rare and most babies
are given a clean bill of health, early diagnosis and proper treatment can
make the difference between lifelong impairment and healthy development.
Newborn Screening: Past, Present, and Future
In the early 1960s, scientist Robert
Guthrie, PhD, developed a blood test that could determine whether newborn
babies had a metabolic disorder known as phenylketonuria (PKU).
People with PKU lack an enzyme needed to process the amino acid
phenylalanine. This amino acid is necessary for
normal growth in infants and children and for normal protein use
throughout life. However, if too much of it builds up, it damages the
brain tissue and can eventually cause mental retardation.
When babies with PKU are put on a special diet
right away, they often can avoid the mental retardation that children with
PKU suffered in the past. By following certain dietary restrictions, these
children can lead normal lives.
Since the development of the PKU test,
researchers have developed additional blood tests that can screen newborns
for other disorders that, unless detected and treated early, can cause
physical problems, mental retardation, and in some cases, death. All
states, the District of Columbia, Puerto Rico, and the U.S. Virgin Islands
now have their own mandatory newborn screening programs. Because the
federal government has set no national standard, screening requirements
vary from state to state, as determined by individual state public health
Consequently, the comprehensiveness of these
programs varies, with states routinely screening for anywhere from four to
30 disorders. The average state program tests from four to 10 disorders.
State requirements tend to change periodically
as well. In fact, the pace of change is speeding up, thanks to the
development of a new screening technique known as tandem mass
spectrometry. This technology, which can detect the blood components
that are elevated in certain disorders, is capable of screening for more
than 20 inherited metabolic disorders with a single test.
Some states are already offering expanded
screening with tandem mass spectrometry through pilot studies. However,
there's some controversy over whether the new technology has been tested
adequately. Also, some experts want more evidence that early detection of
every disease tested for will actually offer babies some long-term
benefit; equally important, parents may not want to know ahead of time
that their child will develop a serious condition when there are no
medical treatments or dietary changes that can improve the outcome. And
some questions about who will pay (states, insurance companies, or
parents) for the newer technology have yet to be resolved.
The American Academy of Pediatrics (AAP) and the
federal government's Health Resources and Services Administration convened
a task force of experts to grapple with these issues and recommend next
steps. Their report identified some flaws and inconsistencies in the
current state-driven screening system and proposed the following:
All state screening programs should reflect
All states should test for the same disorders.
Parents should be informed about screening
procedures and have the right to refuse screening, as well as the right
to keep the results private and confidential.
Parents should be informed about the benefits
and risks associated with newborn screening.
All of this can be a little confusing (and
anxiety-provoking!) for a new parent. The inconsistencies among state
requirements mean that there's no clear consensus on what's really
necessary. On the one hand, it's important to keep in mind that the
disorders being screened for are rare. On the other hand, no parent wants
to take any unnecessary chances with the quality of his or her child's
life - no matter how small the risk.
Traditionally, state decisions about what to
screen for have been based on weighing the costs against the benefits.
"Cost" considerations include:
And states often face conflicting priorities
when determining their budgets. For instance, a state may face a choice
between expanding newborn screening and ensuring that all expectant
mothers get sufficient
prenatal care. Of course, this offers little comfort to parents
whose children have a disorder that could have been found through a
screening test but wasn't.
So what can you do? Your best strategy is to
stay informed. Discuss this issue with both your obstetrician and your
future baby's doctor
before you give birth. Know what tests are routinely done in your state
and in the hospital where you'll deliver (some hospitals go beyond what is
required by state law). You may also want to ask your doctors about
supplemental screening - keep in mind, though, that you'll probably have
to pay for additional tests out of your own pocket.
If you're the parent of an infant and are
concerned about whether your child was screened for certain conditions,
ask your child's doctor for information about which tests were performed
and whether further tests are recommended.
What Disorders Will Be Screened for in My
Newborn screening varies by state and
is subject to change, especially given advancements in technology.
However, the disorders listed here are the ones typically included in
newborn screening programs and are listed in order from the most common
(all states screen for the first two) to least common (ranging from
three-fourths or one-half of states to just a few). Incidence figures
included in this list are according to a 1996 AAP policy statement.
this disorder is detected early,
feeding an infant a special formula low in phenylalanine can
prevent mental retardation. A low-phenylalanine diet will need to be
followed throughout childhood and adolescence and perhaps into adult
life. This diet cuts out all high-protein foods, so people with PKU
often need to take a special artificial formula as a nutritional
substitute. Incidence: 1 in 10,000 to 25,000.
This is the disorder most commonly identified by routine screening.
Affected babies don't have enough thyroid hormone and so develop
retarded growth and brain development. (The thyroid, a gland at the
front of the neck, releases chemical substances that control metabolism
and growth.) If the disorder is detected early, a baby can be treated
with oral doses of thyroid hormone to permit normal development.
Incidence: 1 in 4,000.
Babies with galactosemia lack the enzyme that converts galactose (one of
two sugars found in lactose) into glucose, a sugar the body is able to
use. As a result, milk (including
breast milk) and other dairy products must be eliminated from
the diet. Otherwise, galactose can build up in the system and damage the
body's cells and organs, leading to blindness, severe mental
retardation, growth deficiency, and even death. Incidence: 1 in 60,000
Sickle cell disease is an inherited blood disease in which red blood
cells stretch into abnormal "sickle" shapes and can cause episodes of
pain, damage to vital organs such as the lungs and kidneys, and
even death. Young children with sickle cell disease are especially prone
to certain dangerous bacterial infections, such as
pneumonia (inflammation of the lungs) and
meningitis (inflammation of the brain and spinal cord). Studies
suggest that newborn screening can alert doctors to begin antibiotic
treatment before infections occur and to monitor symptoms of possible
worsening more closely. The screening test can also detect other
disorders affecting hemoglobin (the oxygen-carrying substance in the
blood). Incidence: about 1 in every 500 African-American births and 1 in
every 1,000 to 1,400 Hispanic-American births; also occurs with some
frequency among people of Hispanic, Mediterranean, Middle Eastern, and
South Asian descent.
sickle cell disease
This is actually a group of disorders involving a deficiency of certain
hormones produced by the adrenal gland. It can affect the development of
the genitals and may cause death due to loss of salt from the kidneys.
Lifelong treatment through supplementation of the missing hormones
manages the condition. Incidence: 1 in 12,000.
Babies with MSUD are missing an enzyme needed to process three amino
acids that are essential for the body's normal growth. When these are
not processed properly, they can build up in the body, causing urine to
smell like maple syrup or sweet, burnt sugar. These babies usually have
little appetite and are extremely irritable. If not detected and treated
early, MSUD can cause mental retardation, physical disability, and even
death. A carefully controlled diet that cuts out certain high-protein
foods containing those amino acids can prevent these outcomes. Like
people with PKU, those with MSUD are often given a formula that supplies
the necessary nutrients missed in the special diet they must follow.
Incidence: 1 in 250,000.
Babies with this condition don't have enough biotinidase, an enzyme that
recycles biotin (one of the B vitamins) in the body. The deficiency may
seizures, poor muscle control, immune system impairment, hearing
loss, mental retardation, coma, and even death. If the deficiency is
detected in time, however, problems can be prevented by giving the baby
extra biotin. Incidence: 1 in 72,000 to 126,000.
This metabolic disorder results from a deficiency of one of several
enzymes needed by the brain for normal development. If untreated, it can
lead to dislocated lenses of the eyes, mental retardation, skeletal
abnormalities, and abnormal blood clotting. However, a special diet
combined with dietary supplements may help prevent most of these
problems. Incidence: 1 in 50,000 to 150,000.
Cystic fibrosis is an inherited disorder of the various organs
that causes cells to release a thick mucus, which can lead to chronic
respiratory disease, problems with digestion, and poor growth. There is
no known cure - treatment involves trying to prevent the serious lung
infections associated with it and providing adequate nutrition. Some
infections may be prevented with antibiotics. Detecting the disease
early may help doctors reduce the lung and nutritional problems
associated with cystic fibrosis, but the real impact of newborn
screening is yet to be determined. Incidence: 1 in 2,000 Caucasian
babies; less common in African-Americans, Hispanics, and Asians.
Toxoplasmosis is a parasitic infection that can be transmitted
through the mother's placenta to an unborn child. The disease-causing
organism, which is found in
uncooked or undercooked meat, can invade the brain, eye, and
muscle, possibly resulting in blindness and mental retardation. The
benefit of early detection and treatment is uncertain. Incidence: 1 in
Babies with this disorder have trouble processing the amino acid
tyrosine. If it accumulates in the body, it can cause mild retardation,
language skill difficulties, liver problems, and even death from liver
failure. A special diet and sometimes a liver transplant are needed to
treat the condition. Early diagnosis and treatment seem to offset
long-term problems, although more information is needed. Incidence: not
These are not the only disorders that can be
detected through newborn screening. Certain other rare disorders of body
chemistry can also be detected. Other conditions that are candidates for
newborn screening include Duchenne
muscular dystrophy, a childhood form of muscular dystrophy that
can be detected through a blood test;
HIV; and neuroblastoma, a type of cancer that can be detected with
Should I Request Additional Tests?
Do you have a positive family history of an
Have you previously given birth to a child who
is affected by a disorder?
Did an infant in your family die because of a
suspected metabolic disorder?
Do you have another reason to believe that
your child may be at risk for a certain condition?
If you answered yes to any of the above
questions, talk to your child's future doctor and perhaps a genetic
counselor about requesting additional tests.
If your hospital can't or won't make expanded
screening available to you, and your doctors believe additional testing
would be worthwhile, you may want to contact outside laboratory
services that provide supplemental testing for more than 30 metabolic
disorders through a mail-order service available anywhere in the United
States. The labs send out kits that are used to collect additional blood
at the time of your baby's regular screening, and this sample is then
mailed back for analysis. The cost ranges from $25 to $50.
How Is Newborn Screening Performed?
Within the first 2 or 3 days of life,
your baby's heel will be pricked and a small sample of her blood will then
be applied to a card. Most states have identified a state or regional
laboratory to which hospitals should send the samples for analysis. (If
your hospital offers expanded screening that uses the new technology, your
baby's sample may be sent to a private laboratory.)
It's generally recommended that the sample be
taken after the first 24 hours of life. Some tests, such as the one
for PKU, may not be as sensitive if they are done too soon after birth.
However, because mothers and newborns are often discharged within a day,
some babies may be tested within the first 24 hours. If this happens, the
AAP recommends that a repeat sample be taken no more than 1 to 2 weeks
later. It's especially important that the PKU screening test be run again
for accurate results.
Getting the Results
Different labs have different procedures for sending the results. Some may
send them to the hospital where your child was born and not directly to
your child's doctor, which may mean a delay in getting the results to you.
And although some states have a system that allows doctors to access the
results via phone or computer, others may not. Ask your child's doctor how
you will get the results and when you should expect them.
If a test result should come back abnormal, try
not to panic. This does not necessarily mean that your child has the
disorder in question. A screening test is not the same as diagnostic test.
The initial screening provides only preliminary information that must be
followed up with more specific diagnostic testing.
If testing confirms that your child does have a
disorder, your child's doctor may refer you to a specialist for further
evaluation and treatment. Keep in mind that dietary restrictions and
supplements, along with proper medical supervision, can often avert most
of the serious physical and mental problems that were associated with
metabolic disorders in the past.
You may also wonder whether the disorder can be
passed on to any future children. This is a matter you'll want to discuss
with your child's doctor and perhaps a genetic counselor. Also, if you
have other children who were not screened for the disorder, you may want
to have this done. Again, talk this over with your children's doctor.
Because state programs are subject to
change, you'll want to find up-to-date information about your state's (and
individual hospital's) program. Talk to your child's doctor or contact
your state's department of health for more information.