What is newborn metabolic screening?
What is the heel prick test?
What is a blood spot card or “Guthrie” card?
What are newborn babies screened for?
How many babies are screened each year?
How do I find out about the screening test?
Who takes the blood sample?
Why should my baby have newborn metabolic screening?
My baby seems healthy. Is screening still necessary?
Who should have a newborn metabolic screening test?
When and where should the test be done?
Why is the test done at 48 hours of age?
What are the responsibilities of the Lead Maternity Carer (LMC) in respect to metabolic screening?
What does the test cost?
How will I get my baby's test results?
Can I say no to the test?
Can I get the blood spot card back?
How much blood is used for screening?
What happens to the leftover blood?
What happens to the blood spot card when screening is complete?
Are repeat samples ever needed?
Why are most repeat sample results negative?
What if my baby's test result is abnormal?

What is newborn metabolic screening?
Newborn metabolic screening is a way of identifying babies with an increased risk of having rare but serious disorders known as metabolic disorders. Metabolic disorders do not usually show any signs or symptoms at birth, and are difficult to identify without a blood test. Babies identified through screening as having an increased risk of a disorder need diagnostic testing to confirm if they have a disorder.

Your Lead Maternity Carer or midwife will discuss newborn metabolic screening with you and ask for your consent for it to be done. If you consent on behalf of your baby, a blood sample will be taken as soon as possible after 48 hours of your baby’s age, and before your baby is 72 hours old. A few drops of your baby's blood will be taken from your baby's heel and placed on a blood spot card. Information relating to your baby will be written on the card, and the sample will be sent to the laboratory to be tested for 28 metabolic disorders.

What is the heel prick test?
The ‘heel prick test’ is when a blood sample is taken from a baby’s heel so that the baby’s blood can be tested for certain metabolic disorders.  The blood sample is taken using an automated device called a lancet. The lancet is used to make a small puncture on the side of the baby’s heel. The baby's foot is then allowed to hang down to increase the blood flow, and a blood spot card is used to collect the blood sample. After the “heel prick test” is completed, gentle pressure is applied to the baby’s foot using cotton wool to stop the bleeding.

What is a blood spot card or “Guthrie” card?
A blood spot card, or “Guthrie” card, is a postcard-sized card with special paper (specimen collection paper) for collecting and holding four spots of blood. The blood spot card has two parts, a smaller part with the specimen collection paper for the blood sample, and a larger part for demographic and other information about the baby. The two parts are separated by a perforation. When the card with the blood sample is received by the laboratory, a unique identification number is placed on both parts of the card and the laboratory separates the blood spot part from the rest of the card for testing.

What are babies screened for?
The Newborn Metabolic Screening Programme screens newborn babies for 28 metabolic disorders:

• Amino acid disorders (14 disorders, including PKU and MSUD) 
• Fatty acid oxidation disorders (9 disorders)
• Others:  
  • Congenital hypothyroidism (CH)
  • Cystic fibrosis (CF)
  • Congenital adrenal hyperplasia (CAH)
  • Galactosaemia
  • Biotinidase deficiency.
    

For more information on the disorders click here.

How many babies are screened each year?
Almost all babies born in New Zealand have newborn metabolic screening. 

How do I find out about the screening test?
Your Lead Maternity Carer will talk to you about the screening test and give you the opportunity to ask questions. Your Lead Maternity Carer will also give you a brochure containing information about the Newborn Metabolic Screening Programme . If you agree to the test being done, a few drops of blood will be taken from your baby's heel (sometimes called the "heel prick test" or "Guthrie test") and collected onto a blood spot card. The blood sample is dried and sent to the laboratory for testing.

Who takes the blood sample?
The blood sample is taken by a Lead Maternity Carer, hospital midwife, or trained blood taker (phlebotomist).

Why should my baby have newborn metabolic screening?
Metabolic disorders often do not show any symptoms until damage has occurred. Screening can detect these disorders before symptoms appear, and early treatment can be available to your baby.

My baby seems healthy. Is screening still necessary?
Yes. Most babies with the metabolic disorders screened by this programme show no obvious signs or symptoms immediately after birth. In each of these disorders there is a problem in one of the biochemicals which are produced naturally in the baby's body. Without a blood test these problems are hard to identify. Screening can detect these disorders before symptoms appear, and early treatment can be available to your baby.

Who should have a newborn metabolic screening test?
The Ministry of Health strongly recommends screening for all newborns.

When and where should the blood sample be taken?
The blood sample should be taken at 48 hours of your baby’s age, or as soon as possible after this (and before 72 hours of your baby’s age).  The sample may be taken either in hospital or at home.

Why is the test done at 48 hours or as soon as possible after this?
When a baby with a metabolic disorder is in the womb, the placenta clears away any abnormal biochemical levels as the baby’s system produces them. When the baby is born, the baby’s own system takes over and if the baby has a metabolic disorder, the biochemicals can accumulate to toxic levels or cause other problems. The baby’s own system should be working properly at 48 hours of age, and this is therefore the best time to test the baby for metabolic disorders: when your baby’s system is working independently, and before your baby gets sick.

What are the responsibilities of the Lead Maternity Carer (LMC) in respect to metabolic screening?
The LMC is responsible for:

• talking to parents/guardians about newborn metabolic screening
• answering any questions parents/guardians have about the programme
• ensuring that parents/guardians give informed consent for screening
• recording consent or decline to screening
• ensuring that other health professionals are aware of declines
• taking the blood sample (or ensuring it is taken)
• providing any follow-up required by the programme, such as taking repeat samples and reporting results.
  

What does the test cost?
Newborn metabolic screening is free to all eligible babies born in New Zealand.  See the Ministry of Health website for eligibility criteria relating to publicly funded services.

How will I get my baby's test results?
Your LMC or midwife will have your baby's results within ten days if they are negative. 

If a result is positive, the laboratory will telephone your LMC or midwife and they will let you know as soon as possible so that your baby can be referred to a specialist.

Can I say no to the test?
Yes, newborn metabolic screening is voluntary. Your Lead Maternity Carer or midwife can talk about any concerns or questions you have.  Your health professionals (well child provider, doctor) should be advised if your baby has not been screened.     

 

Can I get the blood spot card back?
Yes, you can ask for your baby's blood spot card back after screening is complete. If you would like to request your baby's blood spot card, please download and complete the form below and send it to the laboratory. You will be sent the top part of your baby’s blood spot card with the specimen collection paper holding the blood sample. Download the form 'Return of newborn metabolic screening samples (guthrie cards) to family'

How much blood is used for screening?
Six small spots of blood are punched out of the card. One of these spots is used to test for 23 of the disorders using the tandem mass spectrometer. The other five spots are used to test for the other five disorders. The leftover blood is either tested again if there is a problem with the first result, held in secure storage or returned to the family/whanau at their request.

What happens to the leftover blood?
Any blood left over after screening may be used:

• for confirmatory testing (if the first test shows an unclear result, another blood spot will be tested) to investigate the cause of false positive and negative results
• for quality assurance monitoring and evaluation
• to make improvements to the screening programme (eg assay improvement)
• to investigate unexplained illness or death in a family/whanau
• for forensic use (identifying a deceased or missing person or assisting with coronial enquiries such as identifying victims of a natural disaster or crime)
• for population-based studies using de-identified samples
• for research projects. To date, research using identifiable blood spots has not been undertaken. However, there is potential for this to happen in the future if blood spots are retained in storage.
  

What happens to the blood spot card when screening is complete?
When screening is complete, the blood spot card is either returned to the family/whanau or held in secure storage. Access to the stored blood spot cards is limited to staff involved with the screening programme.

Are repeat samples ever needed?
Repeat samples are needed for about one in every fifty babies. Repeat samples are needed if there was too much or not enough blood collected, the sample was contaminated or took too long to reach the laboratory, or the result showed an increased risk for one of the disorders.  If this happens with your baby’s sample, your Lead Maternity Carer will contact you and request another blood sample be taken from your baby's heel. 

Why are most repeat sample results negative?
Most repeat samples are negative. This is usually because the first sample had too much or not enough blood, was contaminated (eg with baby powder or lotion), or took too long to reach the laboratory, and the test result was not accurate. If the baby's metabolism is slightly delayed, this may also cause an inconclusive reading. In these cases the repeat sample will usually give a negative result.

What if my baby's test result is abnormal?
There are a number of reasons for an abnormal result. The blood sample may have been contaminated, too much or not enough blood may have been taken, or the sample may not have reached the laboratory quickly enough. The sample may also have been "borderline", which means it was not possible to tell whether or not there was a problem. In these cases, your Lead Maternity Carer will talk to you about taking a repeat sample.

The result may also have been abnormal because your baby has an increased risk of having one of the disorders screened for. If this happens, the laboratory will contact your Lead Maternity Carer. Diagnostic testing will be necessary to confirm the diagnosis. This will be managed by a paediatrician.

Many of the effects of disorders can be reduced - either by diet or medicine - but treatment is best if started early.