About Newborn Screening
Newborn screening is the practice of testing every newborn for
certain harmful or potentially fatal disorders that aren't
otherwise apparent at
. Many of these are
, 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) 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
With a simple blood test, doctors can often 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
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
(PKU). People with PKU lack an enzyme needed to process the amino
acid phenylalanine. This amino acid is necessary for
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
can often avoid the mental retardation that children with PKU
experienced 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,
Most states, the District of Columbia, Puerto Rico, and the U.S.
Virgin Islands now have their own mandatory newborn screening
programs (in some states, such as Wyoming and Maryland, the
mandatory). Because the federal government has set no national
standard, screening requirements vary from state to state, as
determined by individual state public health departments.
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
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
(often abbreviated as MS/MS). This technology can detect the blood
components that are elevated in certain disorders, and is capable
of screening for more than 20 inherited metabolic disorders with a
About half of the states are offering expanded screening with
tandem mass spectrometry on every baby. 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 current
- 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.
How Do States and Hospitals Decide Which Tests to Offer?
Traditionally, state decisions about what to screen for have
been based on weighing the costs against the benefits.
"Cost" considerations include:
- the risk of false positive results (and the unnecessary
anxiety they cause)
- the availability of treatments proven to help the
- financial costs
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
. Of course, this offers little comfort to parents whose children
have a disorder that could have been found through a screening test
So what can you do? Your best strategy is to stay informed.
Discuss this issue with both your obstetrician or health care
provider and your future baby's
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's required by state law).
If your state isn't offering screening for the expanded
panel of disorders, you may want to ask your doctors about
supplemental screening. Keep in mind, though, that you'll
probably have to pay for the additional tests out of your own
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?
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
When 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
) 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 to 80,000. There are several less severe forms of
galactosemia that may be detected by newborn screening. These may
not require any intervention.
Sickle Cell Disease
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
(inflammation of the lungs) and
(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.
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 cause
, 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.
Congenital Adrenal Hyperplasia
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.
Maple Syrup Urine Disease (MSUD)
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.
This metabolic disorder results from a deficiency of one of
several enzymes 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.
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 yet determined. Some babies
have a mild self limited form of tyrosiemia
is an inherited disorder expressed in 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.
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 1,000. But only one or
two states screen for toxoplasmosis.
These aren't 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:
, a childhood form of muscular dystrophy that can be detected
through a blood test
- neuroblastoma, a type of cancer that can be detected with a
Most, but not all states require newborns' hearing to be
screened before they are discharged from the hospital. If your
infant isn't examined at that time, it's important to make sure
that he or she does get screened within the first three weeks of
life. A child develops critical speaking and language skills in the
first few years of life, and if a hearing loss is caught early,
doctors can treat it so that it doesn't interfere with that
Should I Request Additional Tests?
If you answer "yes" to any of the questions below,
talk to your child's future doctor and perhaps a genetic
counselor about requesting additional tests.
- Do you have a positive family history of an inherited
- Have you previously given birth to a child who's affected
by a disorder?
- Did an infant in your family die because of a suspected
- Do you have another reason to believe that your child may be
at risk for a certain condition?
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 filter paper. 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. Some states use a private lab for all of their
It's generally recommended that the sample be taken
the first 24 hours of life. Some tests, such as the one for PKU,
may not be as sensitive if they're 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. Some states
routinely do two tests on all infants.
Getting the Results
Different labs have different procedures for notifying families
and pediatricians of 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.
necessarily mean that your child has the disorder in question. A
screening test is
the same as diagnostic test. The initial screening provides only
preliminary information that must be followed up with more specific
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 weren't screened for the disorder,
you may want to have this done. Again, talk this over with your
Know Your Options
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.
Louis E. Bartoshesky, MD and Steven Dowshen, MD
Date reviewed: June 2006
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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