|
|
|
| You are here: DOH Home » EHSPHL Home » PHL Home » NBS Home »Health Professional's Page | Search | Employees |
| Site Directory: | Health Professional's Page | |||||
|
• NBS News
|
What should I know about the information provided on this page? This information is intended to explain the necessary collaboration between the Washington State Newborn Screening Program, health care facilities and providers to help make newborn screening successful. Included is information about the disorders detected by the program and answers to frequently asked questions about newborn screening, such as the availability of expanded screening, the effects of transfusions, and the storage of newborn screening cards. This information is intended to answer many of the questions health care providers generally have about the screening system. We hope that you will find this information helpful. A pdf version of this information in a manual format can be accessed by clicking the link below. If you have any questions about information contained below or within the manual, please contact us at (206) 418-5410 or NBS.Prog@doh.wa.gov. The Newborn Screening program encourages all patients to discuss any concerns they have regarding newborn screening results with their health care provider or with follow-up staff at the Newborn Screening program. (click here for a pdf version of the information below in manual format) Please see the viewer page for free software to enable viewing of pdf files. Use the subject links below to view topics of interest. Introduction
Newborn screening is a population-based,
preventive public health program that is carried out in every state in the
United States and in many countries throughout the world. It enables early identification of selected disorders that,
without detection and treatment, can lead to permanent mental and physical
damage or death in affected children. The goal of newborn screening is to
facilitate prevention of developmental impairments (such as mental retardation
and neurological deficits), delayed physical growth, severe illness, and death
through early detection and intervention. Across the United States there are variations in the disorders for which each state screens. Infants born in Washington State are currently screened for phenylketonuria (PKU), congenital hypothyroidism (CH), congenital adrenal hyperplasia (CAH), galactosemia, biotinidase deficiency, homocystinuria, maple syrup urine disease (MSUD), medium chain acyl-CoA dehydrogenase (MCAD) deficiency, sickle cell disease and other hemoglobinopathies. Although testing is possible for many other disorders, Washington adds tests to the newborn screening panel only after careful consideration of the following criteria: ·
Prevention Potential and Medical Rationale: Identification
of the condition provides a clear benefit to the newborn - preventing delay in
diagnosis; developmental impairment; serious illness or death. · Treatment Availability: Appropriate and effective screening, diagnosis, treatment, and systems are available for evaluation and care. ·
Public Health Rationale: Nature
of the condition (symptoms are usually absent, such that diagnosis is delayed
and treatment effectiveness is compromised) and prevalence of the condition
justify population-based screening rather than risk-based screening. ·
Available Technology: Sensitive,
specific and timely tests are available that can be adapted to mass screening. ·
Cost-Benefit / Cost–Effectiveness: Benefits
justify the costs of screening. Successful newborn screening requires collaboration between the State Newborn Screening Program, health care facilities (hospitals, local health departments, clinics), health care providers (pediatricians, family practice physicians, nurse practitioners, midwives), and families of newborns. The Washington State Newborn Screening Program is within the Department of Health and is located at the State Public Health Laboratory in Shoreline. It is a coordinated system of screening services comprised of laboratory, follow-up, and support staff. The laboratory personnel: · receive and prepare specimens for testing; · test and analyze each specimen; · record all results and report non-normal results to the follow-up staff; · evaluate and maintain in-house procedures and specimen quality; and · incorporate new technologies by establishing protocol and evaluating the integrity of the screening tests before implementation. The follow-up and support staff: · provide appropriate follow-up and referral to providers for newborns with abnormal screening test results to ensure prompt diagnostic and treatment services; · provide long-term follow-up and tracking of affected children to ensure continued access to appropriate comprehensive health care, including distribution of metabolic treatment products; · verify screening for all newborns and act if screening is delayed; · collect, analyze, and disseminate data on newborn screening requirements including clinical outcomes; and ·
provide consultation, technical assistance and education of
newborn screening to hospitals, health care professionals, families of affected
newborns and the general public. Achieved through the cooperative work of the
above three groups, the responsibilities of the Washington State Newborn
Screening Program are: ·
Rapid,
efficient screening of children born in the state for the nine disorders above. ·
Verifying
that each newborn has had access to screening and if not, taking action to
assure screening is available. ·
Appropriate
follow-up and referral to health care providers for newborns with abnormal
screening test results to facilitate prompt diagnostic and treatment services. ·
Consulting
with health care providers regarding test implications and recommending
follow-up actions. ·
Long-term
follow-up and tracking of affected children to evaluate outcomes of the program,
improve effectiveness and promote continued access to appropriate specialty
health care. ·
Collecting,
analyzing, and disseminating data on newborn screening requirements, including
cost effectiveness of the system and health outcomes. · Consulting, providing technical assistance, and education regarding all components of newborn screening to hospitals, health care professionals, families of affected children, and the general public. The
responsibilities of the health care facilities and providers are: ·
Properly
collecting, labeling, and handling of newborn screening specimens. ·
Documenting
the screening status of each patient. ·
Responding
quickly to information and specimen requests from the Newborn Screening Program. ·
Promptly
following up on infants requiring further testing to rule out or confirm a
diagnosis. ·
Providing
parent education about newborn screening and referral to specialty care services
as needed. The
responsibilities of the families are: ·
Educating
themselves about the newborn screening test that will be performed on the
infant. ·
Reporting
to the health care provider the presence of a family history of any screened
disorder. ·
Responding
quickly to requests from the health care provider or Department of Health for
repeat screening. ·
Working
cooperatively with health care providers and institutions when required for
follow-up. Responsibility for Obtaining a Newborn Screening Specimen Washington State law requires that every newborn be tested prior to discharge from the hospital or within five days of age. The law designates hospitals providing birth and delivery services or neonatal care to the newborn as being responsible for specimen collection. This includes informing the family of the purpose of screening, the legal requirement and the right to refuse. We recommend that physicians, midwives, and childbirth centers that deliver babies out-of-hospital follow the guidelines for hospital births. According to law (Chapter
70.83 RCW – PHENYLKETONURIA AND OTHER PREVENTABLE HERITABLE DISORDERS), a
newborn screening specimen should not be obtained on any newborn infant “whose
parents or guardians object thereto on the grounds that such tests conflict with
their religious tenets and practices”. If
parents do refuse, it is the responsibility of the health care facility to
obtain the signature from the parent(s) on the reverse side of the screening
card to document the refusal. The
provider must make certain that the parent(s) understand the risks of refusing
the screening. As with collected
specimens, the demographic information should be completed and the signed card
forwarded to the Newborn Screening Program within 24 hours.
The refusal should be noted in the infant’s medical record. It is
important to note that religious reasons are the only valid basis for refusal.
Newborn screening statistics indicate that the majority of infants whose
parents signed a refusal in the hospital were later tested, indicating that the
initial refusal was not truly based on religious principles.
Affected infants could have a delayed diagnosis for several days or
possibly weeks, thus placing them at significant risk of permanent damage or
possibly death. The risk of refusal should be made clear to parents and refusals
should not be accepted for any other reason. In addition to the required
first specimen, it is strongly recommended that every baby born in Washington
have a second screening specimen collected between 7 and 14 days of age.
This recommendation has been carefully considered relative to the
specific disorders included in Washington’s Newborn Screening Program.
Laboratory detection of each of the nine disorders has its own special
problems related to the ideal time for testing, hence the recommendation for two
specimen collection times. Both the
first and second dried blood specimens receive the same battery of tests at the
State Laboratory. The first screen
is essential for making an early diagnosis necessary to prevent a salt-wasting
crisis in a child with CAH, a fatal bacterial infection in a baby with
galactosemia or a fatal metabolic crisis in a baby with MSUD.
The second optimizes detection of PKU, CH,
and homocystinuria, which rely on time-dependent
changes in the concentration of substances in blood.
Detection of hemoglobinopathies such as sickle cell disease is not
dependent on the time of collection since testing relies on red cell components
that do not change significantly during the first two weeks of life. Aside
from the fact that the hospital pre-discharge screen is mandated by state law,
the practice of forgoing the first screen with the intent to collect a specimen
at a later date to avoid “sticking the baby twice” is strongly discouraged.
Besides greatly increasing the risk that a newborn screening specimen
will not be obtained (because some infants will not return to the hospital or
appear at a clinic), this practice unnecessarily delays diagnosis and treatment
of affected infants, the majority of whom will be detected by the first
screening, regardless of the disorder. We
are aware that, due to the increasing trend of early hospital discharge, the
first well-baby visit with the primary health care provider is also being
scheduled earlier. The standard of care for collecting the second specimen is
still 7-14 days. However, in view
of the increasing frequency of earlier first visits and possible uncertainty
that the child will not be seen during the 7-14 day period, we are now
recommending obtaining blood for the second newborn screen at the first
well-baby visit, provided it is at least 48 hours after collection of the first
specimen and it is a hardship for the baby to return to the hospital or clinic
again between 7 and 14 days. It
is extremely important that all requested information on the specimen card be
filled out completely and accurately.
This information is critical to interpreting the test results and
facilitating rapid communication of results back to the submitter.
Please contact the Newborn Screening Program at (206) 418-5410 to order
specimen cards free of charge.
A pamphlet for parents and a mailing envelope is also provided with each
specimen card ordered. Print all information using black or blue ink and stay within the limits of the designated boxes. Try to avoid touching the filter paper while completing the form as this could affect the results. A copy of the current card is below:
While
all fields of the newborn screening card are important, we have noticed problems
with compliance in the following areas as numbered above. 1.
The mother’s first and last names are used to link the first and second
newborn screening specimens at the Newborn Screening Program. This linking may
not occur if this information is different on the two specimen cards.
Without this linkage the Newborn Screening Program may contact the health
care provider unnecessarily to collect an additional specimen.
Please be sure to use the mother’s last name in this section if mother
and child have different last names.
If the mother’s name is too long to fit into the boxes provided,
continue printing the name outside of them. 2.
The submitter listed on the specimen card is the health care facility or
provider that collected the specimen and will receive the results after
screening.
Please write both the full name and the ID number. The ID numbers for
hospitals are listed on the back of the screening card.
For other ID numbers please contact our office at (206) 418-5410. 3.
Rapid follow-up of an abnormal screening test depends upon identifying
the health care provider who is caring for the child.
This provider should be the one that the child will be seeing for primary
care, such as a pediatrician, rather than the provider who cared for the child
after birth, such as a neonatologist.
Every effort should be made to ensure that the primary health care
provider’s information is accurate and complete.
Please list both the name and the ID number of the provider.
Check our
regional provider directories for your provider number or contact our office at (206) 418-5410 if you are not certain of
your provider number.
Some providers do not have an ID number (i.e. medical residents or
fellows).
In this case, please write the name of the facility that will be
providing follow-up care in either this section or the Optional Use section. 4.
The age of the infant at the time of collection is important in the
interpretation of the screening results.
The date of birth and date of collection should include the month, date,
and year as well as the time of day. 5.
Birth weight should be entered in either pounds or grams (preferably in
grams), but not both.
Please indicate the weight of the child at birth, rather than the weight
of the child at the time of specimen collection.
This information is important in the interpretation of the screening
results. 6.
The transfusion status of the child effects the screening results,
particularly that of galactosemia and hemoglobinopathies.
If the child has had a transfusion, please indicate on the card the date
of the most recent transfusion.
When this box is checked, the screening results will not contain
information on hemoglobin or galactosemia, as it will not be accurate.
For more information on how transfusion status affects screening, please
see page 20. 7.
For the child’s race, check all that apply.
Include Aleut and Eskimo under Native American and all of the following
under Asian: Asian Indian, Cambodian, Filipino, Guamanian, Hawaiian, Japanese,
Korean, Laotian, Samoan, and Vietnamese.
The guidelines for assigning race are also listed on the back of the
newborn screening collection card.
In addition to race, please indicate whether or not the child is of
Hispanic ethnicity. 8.
If a parent or guardian refuses the newborn screening test, please check
the box at the bottom of the card and have the parent or guardian sign the back
of the card.
In this case, please complete the information on the card as you would if
blood had been collected.
For more information on refusals, please see page 7. The
following specimen collection instructions are based on the approved standard
published by NCCLS (National Committee for Clinical Laboratory Standards).
If you have any questions regarding other techniques, please contact us
at (206) 418-5410. The
following equipment will be needed for specimen collection: a sterile,
disposable lancet with a depth less than 2.0 mm, a sterile 70% isopropyl alcohol
pad, sterile gauze, a soft cloth, the blood collection form, and gloves. Gloves
should be worn for personal safety.
To prevent specimen contamination, do not touch the blood collection
filter paper circles with gloved or ungloved hands, alcohol, formula, water,
powder, antiseptic solution, lotion, or other substances. After confirming the identity of the infant, place the infant’s feet lower than the level of the heart in order to increase blood flow to the foot. To increase the blood flow at the puncture site, warm the heel for three to five minutes using a moist towel at a temperature no greater than 41°C. (Temperatures greater than this can burn the infant’s skin.) Select
the puncture site.
This should be the lateral or medial plantar surface of the heel,
illustrated below. Do
not use previous puncture sites or the area at the heel curvature.
The puncture must not be performed on the central area of the foot.
This may result in damage to the nerves, tendons, and cartilage of the
foot. Cleanse
the puncture site with the sterile alcohol pad and allow the heel to air dry.
Using the sterile lancet, perform a swift clean puncture.
Wipe away the first drop of blood with a sterile gauze pad.
Allow another large drop of blood to form.
To enhance blood flow, apply very gentle intermittent pressure with the
thumb to the area surrounding the puncture.
Avoid excess squeezing or “milking” as it contaminates the blood
sample with tissue fluid. Lightly
touch the blood drop to the filter paper circle and allow a sufficient quantity
of blood to soak all the way through the paper to completely fill the circle.
Do not press the paper against the puncture site.
Apply blood to one side of the filter paper only and allow full
saturation before continuing with the next circle.
Do not apply successive drops of blood to the same circle.
If a circle cannot be filled due to diminished blood flow, repeat the
procedure on a new circle.
Repeat this until all circles are filled.
It is important that complete saturation occurs for each circle due to
the quantitative measurements used during screening.
Results are based on a specific blood quantity within a particular sized
sample.
When blood does not soak completely through, the results are not
comparable to lab standards and will be returned to the submitter as unsuitable. After
blood collection, elevate the foot above the body and gently press the puncture
site with a sterile gauze pad or cotton swab until the bleeding stops. Although
the heel stick procedure is preferable, use of sterile heparinized capillary
tubes for blood collection is acceptable. (Obtaining blood from an infant’s
finger is not an acceptable method of collection.)
Follow the above procedures and apply approximately 75-100 ml
to each circle, using a new tube for each circle.
Touch the tube to the formed blood drop and apply a single application
immediately to the paper. Do not touch the capillary tube to the filter paper
when applying the blood; this will scratch or abrade the sample invalidating it
for screening.
(Note: the blood sample must not be applied to the filter paper as EDTA
or citrate blood due to the chelating effect on europium.) Blood
collection from the dorsal hand vein is also an acceptable blood collection
technique.
However, do not use a vein into which IV fluids or blood are being or
have been infused since this will contaminate the specimen.
After venipuncture, follow the step outlined above for the heel puncture.
Click here to view a poster of these procedures. Click here to view a poster on specimen acceptability. Allow
the blood to air-dry on a flat, clean non-absorbent open surface for at least
three hours at ambient temperature.
Keep the specimen away from direct heat or sunlight and do not
refrigerate the specimen.
Do not store in a plastic bag as this invalidates the specimen due to
unknown effects of condensation and degradation of the blood.
When completely dry, merely fold (do not tape or staple) the flap with
the biohazard label
over the blood circles and double check that all information has been
completed. Place
the card into the envelope provided.
If sending more than one specimen, we recommend using an envelope for
each card; otherwise, alternate the cards so that the blood specimens do not
come into contact with one another. (Please do not place more than six
collection cards in a single envelope.)
As
required by law, send specimens to the Newborn Screening Laboratory within
24 hours of collection.
Do not “batch” specimens from several days as this can significantly
delay diagnosis of an affected child and may result in specimens being too old
to test when they arrive. For
high priority specimens (i.e., infants with relatives affected with a disorder
screened or those needed to confirm a clinically significant finding), overnight
shipment is available via Federal Express.
Call us at (206) 418-5410 to arrange for this shipping.
Screening results will be sent to the submitter of the specimen. These results are to be used as a record for the child’s medical chart. Please carefully read the results for each child to verify that the specimen was suitable for testing and that no further testing is necessary. This information should ideally be forwarded to the child’s health care provider, especially if the results were abnormal or unsuitable. If
the results are not received for a specimen that you submitted within three
weeks, please contact the Newborn Screening Program at (206) 418-5410, or fax
your request to (206) 418-5415.
Before calling, however, please verify that the results have not been
misfiled, for example, under the mother’s name. If
you are requesting results for a specimen that you did not submit, i.e., to
verify that a first or second test has been done, please contact
the health care facility or provider that submitted the specimen, if
known, prior to contacting the Newborn Screening Program..
Screening
results fall within three broad categories: normal, abnormal, and unsuitable.
Results are typically mailed within five days of the Newborn Screening
Laboratory receiving the specimen. Over
90% of the results will be mailed within five days, while over 99% will be
mailed within seven days. These
results will be sent to the submitter of the specimen.
If you receive a result report or letter that does not belong to a
patient within your facility, please mail or fax the results to the Newborn
Screening Program indicating such (See Appendix B for contact information). Normal ResultsNormal
results will be sent to the submitter to be placed in the child’s medical
record. It is important to note
that normal findings on the first test should not prevent a second specimen from
being collected. As previously
mentioned, the first screen is essential for making an early diagnosis necessary
to prevent salt-wasting crisis in a child with CAH, a fatal bacterial infection
in a baby with galactosemia or a fatal metabolic crisis in a baby with MSUD, and
the second optimizes detection of PKU, CH, and homocystinuria, which rely on
time-dependent changes in the concentration of substances in blood.
In addition, if a child with normal findings develops clinical symptoms,
the screening results should not prevent further testing. Abnormal ResultsAbnormal screening results include borderline and presumptive positive levels of analytes for PKU, CH and CAH, galactosemia, biotinidase deficiency, homocystinuria, MSUD, MCAD deficiency, as well as hemoglobin disorders and traits. The Newborn Screening Follow-up staff temper the response to abnormal test results by the degree of abnormality and the demographics of the infant. For instance, abnormal results are often secondary to prematurity or early sampling (<24 hours of age). A second specimen is usually all that is required to rule out the presence of one of the disorders screened. For borderline levels or hemoglobin trait results, results are immediately mailed to the submitter with a request for a follow-up screen. If a second specimen is not received within two to four weeks, the child’s primary health care provider will be contacted. In
the event of significant abnormal results, such as presumptive positive levels
or a clinically significant hemoglobin disorder, the primary health care
provider (as indicated on the screening card or by Medical Records at the
child’s facility of birth) is immediately contacted and appropriate
recommendations for further testing are made.
This may involve submitting another newborn screening specimen or
following up with diagnostic testing and referral to a medical specialist. All abnormal results are also reported by mail to the
submitter with a note indicating the follow-up actions taken. Unsuitable SpecimensThe
Newborn Screening Program receives some specimens that are unsuitable for
testing.
While the laboratory does test unsuitable specimens for extreme
values when possible, improper collection compromises the accuracy of the test
results.
This delays the screening and diagnosis of the newborn and
requires that a repeat specimen be submitted as soon as possible.
Please see the specimen acceptability page for the various causes of unsuitable
specimens.
The linked Acrobat pdf file contains an example of the format in which results are mailed to submitters. These reports are mailed to the submitter upon completion of laboratory testing.
(Click
here to view sample mailer) The first page is an address
cover sheet.. The second page contains the
results for an individual child. The
State lab number for that child is listed on the top left and is followed by the
demographic information as completed on the newborn screening card by the
submitting facility. The next
section contains the screening results for the nine disorders, including the
laboratory result and the classification. The
third page contains more detailed information on non-normal results and is not
present for most results. It may
contain further interpretation of the result, recommendations for follow-up, and
actions taken by the Newborn Screening staff. It is important that this page be
stored with the results on the previous page.
The Newborn Screening Program sometimes receives screening cards with incomplete demographic information required for follow-up, such as the name of the primary care provider. To obtain this information, the hospital or other known health care provider is contacted. The information that is provided is kept confidential, as is the information on the screening card. Prompt responses to requests for information are appreciated. The first newborn screening specimen should be obtained prior to transfusion whenever possible. Specimens collected following red blood cell transfusions will yield invalid results for galactosemia and hemoglobinopathy screening. In the event that the first screening specimen is collected after a transfusion, please note this on the screening card to assist the laboratory in interpreting the results and recommending follow-up procedures. The galactosemia status and hemoglobin phenotype can be determined after the transfused cells have cleared. A specimen collected four to six weeks after the last transfusion will resolve galactosemia disease status and hemoglobin phenotype in most circumstances. The first and second specimens should still be collected within the recommended times because the detection of the other seven disorders is not affected by the transfusion. To download a one page synopsis of these special considerations for NICU and Special Care Nurseries click here. The
Washington State Newborn Screening Program recommends an additional specimen
collection for sick and premature infants. This includes infants weighing less
than 1500 grams at birth and sick infants requiring a hospital stay of three
weeks or more. The standard of practice for newborn screening in Washington
State is for all infants to have two heelstick specimens collected and sent to
the State Public Health Laboratory for testing. The first specimen is mandatory
and must be collected before discharge from the hospital or by five days of age
if the infant remains in the hospital beyond the usual stay. The second specimen
should be collected between seven and fourteen days of age. Recent
studies and our own experience in Washington State indicate that premature and
sick infants with congenital hypothyroidism can have a late onset of thyroid
stimulating hormone (TSH) elevation that may not be detected on the second
specimen. It is thought that this delay may be caused by immaturity of the
thyroid gland or receipt of transfusions and medications. Because
elevated TSH is the most specific screening indicator for congenital
hypothyroidism, it is recommended that a third newborn screening specimen be
collected from premature and sick infants between four and six weeks of age or
just prior to hospital discharge, whichever is sooner. This specimen should be
in addition to the two specimens recommended for all infants. There is no extra
charge for the additional specimen; our one-time fee covers all testing that may
be needed.
To download a one page synopsis of these special
considerations for NICU and Special Care Nurseries
click here.
As the hospital of birth is legally responsible for the
screening, that hospital should ensure that the facility of transfer is aware of
the screening status. This
should be documented in the infant’s records at transfer.
If there is no record of screening, a specimen should be obtained as soon
as possible. This also applies to
infants who are transferred to or from a hospital outside of Washington State.
Parents Who Do Not Reside in Washington State
For infants who will not reside in Washington State after
discharge from a Washington hospital, it is important that this is noted on the
newborn screening card in addition to the name of the follow-up provider.
For babies being adopted, please indicate the adoption agency or the infant’s adoptive name (if known) on the newborn screening specimen card so they can be contacted if follow up is necessary. This information can be noted in the Optional Use section of the screening card. This expedites follow up when the first test has the birth mother’s name and the second has the adoptive mother’s name. In this situation, the two tests would not be linked and would be treated as two different infants. Information on adoptions will be kept confidential as is all information provided to the Newborn Screening Program. As with all laboratory tests, newborn screening testing may yield false negative results. Regardless of the results of the newborn screen, the child’s health care provider should proceed with diagnostic testing on any infant exhibiting clinical signs and symptoms. Please alert the Newborn Screening Program in this situation. Infants with Affected Relatives For any infant with a relative affected with one of the newborn screening disorders, providers should alert the Newborn Screening Program so testing can be expedited. In addition, providers should contact an appropriate medical specialist, ideally prenatally, to determine if any diagnostic testing or genetic counseling is indicated. Some children are not tested at birth, including those who immigrate into the United States. In addition, there may be children for whom screening status is not known, including children adopted from another state. We recommend that a specimen be obtained for these children at the first provider visit. Screening older children is valid for most of the disorders. It is very important that the date of birth be written on the card so that the results may be correctly interpreted. As
previously mentioned, there are other disorders that may be screened for at
birth that are not included in as part of the Washington State newborn screen.
If the family is interested in obtaining expanded newborn screening
beyond what we offer, there are laboratories that will perform testing on
specimens for a small fee.
Pediatrix Screening (866-463-6436),Baylor University Medical Center
(800-422-9567), Mayo Medical Clinic (800-533-1710) and University of Colorado
(303-315-7301) will perform supplemental screening for over 20 metabolic
disorders using a kit ordered by providers or parents.
Please contact them for further information.
The Newborn Screening Program retains the specimen card for 21 years after the birth of the child. We retain these forms as a part of the child’s health care records consistent with requirements for hospital records for minors. As health care information, these specimens are protected by confidentiality and cannot be used for purposes other than newborn screening without informed consent by the parents and/or child or by a properly executed subpoena (Chapter 70.02 Revised Code of Washington, Medical Records - Health Care Information Access and Disclosure). Such uses have included testing the specimen for a disease diagnosed in the child later in life. For more information on this issue please use the NBS Privacy Policy page. The Newborn Screening Program is a self-supporting fee based program. A fee is charged for each infant tested through birthing facilities. This is a one-time fee and is charged per infant screened, not per specimen. The fee funds all activities of this comprehensive program. Diagnostic testing, if necessary, will involve additional costs. For the current amount of the fee, please see the NBS Home Page. There are currently ten disorders screened for in the newborn in Washington State: biotinidase deficiency, congenital adrenal hyperplasia (CAH), congenital hypothyroidism (CH), cystic fibrosis (CF), galactosemia, hemoglobinopathies (HB), homocystinuria, Maple Syrup Urine Disease (MSUD), Medium Chain Acyl co-A Dehydrogenase (MCAD) deficiency and phenylketonuria (PKU).
Phenylketonuria (PKU) was the first disorder screened
for at birth and marked the beginning of newborn screening.
PKU is characterized by the inability to metabolize the essential amino
acid phenylalanine due to the lack of the enzyme phenylalanine hydroxylase.
If untreated, PKU results in severe neurological and developmental
damage. Although the exact
pathogenesis of the damage to the central nervous system is still not clear, it
seems likely that an increased concentration of phenylalanine in the blood is
associated in some way with the neurodegenerative effects.
Treatment consists of a special diet low in phenylalanine.
Affected infants develop normally with early identification and proper
dietary management. The prevalence
of PKU in the United States is approximately 1 in 10,000-25,000. In Washington
State, there are, on average, seven infants with PKU detected each year. Clinical Features
Infants with PKU appear
normal at birth. The symptoms of
untreated PKU develop gradually, so they may not be noticed until irreversible
mental retardation has occurred. The
most
common symptoms of untreated PKU are a “musty” odor to the skin and urine,
increased muscle tone and tendon reflexes, an eczema-like rash, and progressive
neurological damage. With early
treatment virtually all symptoms of the disorder are eliminated. Etiology
PKU is caused by a genetic deficiency in the enzyme
phenylalanine hydroxylase, which metabolizes the common amino acid phenylalanine.
It is inherited in an autosomal recessive fashion. Laboratory Tests The PKU screening is no longer performed by the bacterial inhibition assay developed by Dr. Robert Guthrie, commonly known as the “Guthrie test.” Screening is now done using a technology called tandem mass spectrometry (MS/MS). The levels of phenylalanine and tyrosine in the blood spot are measured by a tandem mass spectrometer. Infants are considered to have a presumptive positive test for PKU when they have blood phenylalanine levels of 240 mmol/L (equivalent to 4 mg/dL) or more and a phenylalanine-to-tyrosine ratio of 2 or greater. Laboratory
Result Classifications and Corresponding Follow-up Actions for PKU
|
