Neonatal Screening

Dot Point Summary

Newborn screening is a public health programme aimed at early identification of conditions for which early intervention can lead to elimination or reduction of associated mortality, morbidity and disabilities in newborn babies and often into childhood
A 'well looking baby' may quickly become critically ill
Screening tests are not diagnostic and therefore follow up testing is always required for abnormal results
Not every affected child will be detected by the screening programme, so if one of the screened conditions is suspected, follow up diagnostic testing should be always be considered
Timing of taking the sample is important
The infant's care giver will not be notified if the result is normal

Principles of Newborn Screening

each condition is a serious disorder
occurs with sufficient frequency for screening to be cost effective
cheap reliable screening test is available
early treatment/intervention is beneficial
consequences of non-treatment may be severe

Conditions screened

Phenylketonuria (since 1965)
Congenital hypothyroidism (since 1977)
Cystic Fibrosis (since 1989)
Various inborn errors of metabolism (since 2002)

Phenylketonuria (PKU)

see: OMIM database

5-6 cases per year in Victoria
inherited as an autosomal recessive condition
due to a deficiency of the enzyme phenylalanine hydroxylase
an inability to convert phenylalanine (an amino acid) into tyrosine
can result in severe, progressive intellectual disability
newborn screening also occasionally detects milder variants and other enzyme deficiencies that secondarily affect phenylalanine metabolism
early detection and treatment of PKU with a diet low in phenylalanine (very low protein and special formula) enables normal growth and development
affected children are managed by the metabolic team at Royal Children's Hospital and monitored with regular blood tests

Congenital Hypothyroidism

approximately 20 babies diagnosed per year in Victoria
generally not inherited
usually caused by absence or poor functioning of thyroid gland
lack of thyroxine causes severe intellectual disability and growth problems
easily treated safely with daily oral thyroxine supplements

Cystic fibrosis (CF)

see: OMIM database

approximately 25 babies diagnosed per year in Victoria
inherited as an autosomal recessive condition
a severe genetic condition resulting in the production of thick mucous in lungs and digestive system which results in respiratory infections and difficulty in digesting food properly
screening involves a 3 step process and takes 4 to 6 weeks
- an enzyme level (immunoreactive trysinogen) is measured from the neonatal screening card
- if the enzyme is increased, a genetic test is performed for the most common CF mutation
- a sweat test is performed if only one copy of the mutation is present to determine whether the diagnosis is CF or the baby is a healthy carrier
early detection and treatment improves the health of babies and allows identification of other family members at risk of having a child with CF

Various inborn errors of metabolism

25 different metabolic conditions are detected by tandem mass spectrometry testing
approximately 11 babies diagnosed per year in Victoria
MCAD (medium chain acyl CoA dehydrogenase deficiency - see OMIM database), a defect in fatty acid oxidation, is the most frequent
various treatments including special diets and vitamin supplementation
affected children are managed by the metabolic team at Royal Children's

Pre-test Procedure

give information brochure to parents
discuss newborn screeing test with parents
- screening for many conditions
- may have to give a second sample
- most second samples are within the normal range
- parents contacted to arrange further testing if necessary
gain verbal consent and document

Consent/Refusal

verbal consent required from parents
if parents refuse test on behalf of their baby
- confirm the parents have received the Newborn Screening Program information brochure and that staff have discussed the test with them
- a medical staff member of the treating team must meet with the parents and clearly outline the benefits of the newborn screening test and the risks of not having it done. This is to ensure the parents have a good understanding of possible consequences
- parents must be offered the opportunity to have a discussion with a Newborn Screening Counsellor if they wish. This can be done by ringing the GHSV Reception on 8341- 6201 and asking to be put through to a Newborn Screening Counsellor. Counsellors are best contacted during working hours. An answering machine will take messages. The Newborn Screening Counsellor should be contacted as soon as possible
- the newborn screening card should be filled out with the relevant infant details and "REFUSAL" written in red across the card and sent to the Newborn Screening Laboratory
- document the refusal for the test in the Child Health Record Book
- refusal and nature of discussion should be documented and signed in the mother's and/or baby's file
- advise the parents that in the event that the infant becomes unwell, they should seek medical advice and inform their GP/Paediatrician that their infant has not had a newborn screening test

Sample collection

complete all information on card prior to collection
consider giving sucrose for pain management
collect blood at 48-72 hours post delivery (not 'day 2')
capillary blood sampling is the preferred method for sampling, ensure that the limb chosen has adequate perfusion (if arterial blood is used it should be collected in a non-heparinised syringe)
venous blood is an acceptable alternative
cleanse heel with alcohol swab
wear gloves
ensure baby is peripherally warm before heel prick
air dry heel or wipe dry with sterile gauze pad
press lancet into heel firmly at slight angle
puncture heel - either side of midline, on edge of plantar surface
wipe away first drop with sterile gauze pad
have heel dependent, facing down
wait for spontaneous free flow of blood
apply gentle pressure to heel with thumb, ease intermittently
don't rush - allow time for a large drop of blood to form
lightly touch circle on back of card to large blood drop
allow blood to soak through and completely fill circle
fill each circle with a single application of blood
air dry blood spots on a flat non-absorbent surface
dry for a minimum of 4 hours
check completeness of identification and sufficient blood
do not allow cards to come into contact with contaminated skin or surfaces
mail card(s) without delay

Other points to consider relating to sampling technique

blood spots should not be overlayed on the card. This will contaminate the specimen with tissue fluids
only soak blood from the back of the screening card
the card should not be rubbed on the heel and the blood spots should not be pressed with fingers. This invariably abrades or compresses the card and reduces its blood holding capacity

Timing of the Test

All newborn infants are screened regardless of gestational age, weight, feeding or health status between 48 - 72 hours of life.

Further screening may be required

infants who have commenced Total Parenteral Nutrition (TPN)
- take initial sample at 48-72 hours. Mark "TPN" box on screening card
- repeat the sample 48 hours after cessation of TPN

infants receiving palliative care.

This may help to exclude diseases which may have implications for the family in future pregnancies. If the sample is taken after the infant dies, write in red on the screening card that it is a "post mortem" sample as there is a marked difference in the metabolic profile between a live and a deceased infant.

infants receiving blood products (including blood/exchange transfusions, platelets, fresh frozen plasma (FFP))
- sample should be obtained if possible prior to the transfusion (even if this is less than 48 hours of age)
- 2nd sample at least 48 hours after the transfusion when biochemistry is stable
- 3rd sample is collected three weeks later as the genetic profile will be stabilised

infants born after "in-utero blood transfusion"
- obtain a sample 48-72 hours after birth. This is when the mother's/donor's influence on metabolites has ceased.
- 2nd sample 3 weeks later

extremely low birth weight or premature infants a 2nd sample should be repeated after the initial specimen to detect those infants where immaturity of the hypothalamic-pituitary-thyroid axis may initially mask primary congenital hypothyroidism.
- Birth weight < 1000 grams - 2nd specimen collected at 3 weeks
- Birth weight < 1500 grams - 2nd specimen collected at 2 weeks

If in doubt or you have any queries, contact Newborn Screening Laboratory: 8341-6272

Special Considerations

Parents may request to have their infant's newborn screening returned to them after two years. For further information contact the Newborn Screening Laboratory.

Parents may requests for no secondary access to the card without their permission. This prevents the card being used for other purposes, e.g. development of new tests, ethics approved research. For further information, contact the Newborn Screening Laboratory.

Further Information

Genetic Health Services Victoria

Telephone: (03) 8341 6201
Facsimile: (03) 8341 6390

Newborn Screening Laboratory

Telephone: (03) 8341 6272
Facsimile: (03) 8341 6389

The OMIM database is a useful starting point for learning more about these conditions.

Initially published 30 August 2006 .Last revised 5 June 2010.

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