Newborn metabolic screening is a free test that screens for over 20 rare but potentially serious conditions that can make your baby very sick. The screening test is also called the ‘heel prick’, ‘Guthrie’ or ‘PKU’ test.
The screening test is done when your baby is 24 hours (1 day) old or as soon as possible after this – it can be done in hospital or at home. Your midwife will collect a small amount of blood from your baby’s heel onto a blood spot card.
Finding out early that your baby has a condition means that treatment can start quickly, before your baby becomes sick.
It is your decision to have your baby screened. Around 99% of babies in NZ are screened. The Ministry of Health strongly recommends screening for your baby.
About metabolic disorders
Most babies with these rare disorders appear healthy. Metabolic disorders are hard to find without screening.
Metabolic disorders are usually inherited from one or both parents. Sometimes these genetic disorders are not inherited but first appear in this baby. Each disorder is caused by a different genetic condition and affects different processes in the body.
The current conditions screened for are:
- amino acid disorders (eg, phenylketonuria (PKU) and maple syrup urine disease)
- fatty acid oxidation disorders (eg, MCAD)
- congenital hypothyroidism
- cystic fibrosis
- congenital adrenal hyperplasia
- galactosaemia
- biotinidase deficiency
- severe combined immunodeficiency (SCID).
Finding out early that your baby has a condition means that treatment can start quickly, before your baby becomes sick.
The test
The test is done by your midwife or nurse when your baby is 48 hours (2 days) old or as soon as possible after this. It can be done in hospital, at home or in some laboratories.
Your midwife will collect a small amount of blood from your baby’s heel onto a blood spot card that is then sent for testing.
Results
Your midwife (or specialist doctor) will discuss your baby's test results with you.
Negative results are sent to your midwife within 10 days of sending away your baby’s blood sample.
Positive results for the more serious conditions will be sent to your midwife within several days of sending the sample away. Another sample will be taken and/or your baby is referred for additional diagnostic testing.
If your baby has one of these disorders, you will receive information about the disorder and how it can be treated from a paediatrician who will explain the process and results.
Treatment is best if started early and may include diet or medication.
If you are concerned about your baby's health at any time, talk to your midwife or another health practitioner.
Storage and uses of leftover blood spots
When your baby has the test, you will need to decide whether the leftover blood spots are stored or returned to you after screening.
Stored leftover blood spots may be used for the purposes below. These uses are rare, but they can help families/whānau and the programme.
Any blood left over after screening may be used:
- for repeat testing – if a baby has a disorder but did not have a positive screening result, the blood sample can be tested again to see why this happened
- to make improvements to screening programme tests
- to investigate unexplained illness or death in the individual or family/whānau (with consent)
- for forensic use (identifying a deceased or missing person or assisting with enquiries such as identifying victims of a natural disaster or crime). Access to blood spot cards by New Zealand Police is rare and only as a last resort. It is governed by a Memorandum of Understanding.
- for research approved by an ethics committee and by the Ministry of Health as an appropriate use of residual blood spot samples. Residual blood spots collected prior to June 2011 also require written consent from each individual for use in research.
Requesting the return of a blood spot card
If you would prefer your baby’s sample to be returned to you, download and complete this form. Cards can be requested at any time.
There is a separate form for requesting the return of the sample if your child has died.
The card will be couriered to you within 28 days of your request.
DNA and stored data
As part of metabolic screening, about 1% of samples are currently tested for a change in DNA (mutation) associated with cystic fibrosis. No other DNA testing is done on samples unless authorised by the parents/guardians/individual or through legal avenues (eg, a court order).
Related websites
Tell us your story - Celebrating 50 years of Newborn Metabolic Screening
A series of unique videos have been produced of families who have benefited from metabolic screening, and key figures who have influenced and been involved with the programme over time.
Your newborn baby’s blood test – National Screening Unit
This resource explains how newborn metabolic screening works, and what disorders are screened for.
Autosomal Recessive Inheritance parent information resource – National Screening Unit
The information in this resource will help you understand more about autosomal recessive inheritance and answer some of your questions.
