Newborn bloodspot screening

In many countries, every newborn baby is offered a test for rare but serious medical conditions. This is called newborn bloodspot screening, and is also known as the ‘heel prick test’. The exact list of conditions screened for varies from place to place, but it commonly includes:

• phenylketonuria (PKU)
• hypothyroidism
• cystic fibrosis
• congenital adrenal hyperplasia (CAH)
• other rare genetic conditions

These conditions usually show no symptoms at birth, and there is often no family history. Testing for them early is very helpful, because starting treatment as soon as possible can prevent further health problems (complications).

Consent#

A midwife or other health professional will offer the test, usually at the hospital where your baby was born, or at home. If you want your baby to have the test, you will be asked to agree in writing — this is called giving your ‘informed written consent’.

If you do not want your baby to have the test (called declining the test), you will usually be asked to sign a statement to show that you understand the risks of not having it.

Why screening matters#

The conditions screened for are rare. But if a baby has one of them and it is not found or treated, they could become permanently disabled or even die. By the time symptoms appear, a condition may already have affected your baby’s development. Screening helps affected babies to be identified early, and in most cases they can have treatment to reduce the impact of the condition.

What happens during the test#

Usually, a blood sample is taken between 48 and 72 hours after birth. The midwife pricks the baby’s heel and places a few drops of blood onto a piece of card. This can be done in hospital or at home.

The test is safe and will not harm your baby. The heel prick may cause brief discomfort, but holding or feeding your baby during the sample collection can help. There is a small risk of infection, but the midwife will wear gloves and clean the heel first to keep this risk as low as possible.

The blood sample is examined in a laboratory and tested for different chemicals that show a condition is present. These chemicals are called markers. Levels of biochemical markers for the conditions are measured in the blood spots. Genetic testing is generally done only on a small number of samples (about 1 per cent) that show an increased level of the marker for cystic fibrosis; if that marker is found, the sample is tested for the cystic fibrosis gene.

Test results#

Most babies have a normal result, and you will not be contacted if the result is normal.

Sometimes a repeat test is needed — for example, if the first sample:

• was collected too early
• was contaminated
• produced an unclear result

Don’t worry if this happens, as most repeat screening results are normal.

If your baby has a positive screening result (showing evidence of a condition), you will be contacted and referred to a specialist for further testing. Positive screening results are usually confirmed by testing a sample of urine or blood, and you will be contacted promptly to arrange treatment if needed.

Conditions detected by screening#

Some of the conditions that can be detected include:

• Phenylketonuria (PKU) — a condition where the body cannot break down phenylalanine (found in food proteins). If untreated, PKU can lead to intellectual disability.
• Hypothyroidism — a condition where the thyroid gland does not make enough hormones. This can cause severe intellectual disability and growth problems. Early detection and treatment help children stay healthy.
• Cystic fibrosis — a condition where organs such as the lungs and pancreas make abnormal mucus that clogs them and stops them working properly.
• Congenital adrenal hyperplasia (CAH) — a condition affecting the adrenal glands, which produce a number of key hormones important for the body’s function, including a child’s growth and development. CAH can be treated when detected early. (The classic type is screened; non-classic or late-onset CAH is generally not.)
• Other rare conditions — there are many other rare conditions that make the body unable to break down proteins and fats in the usual way.

If these conditions are found and treated early, before your baby becomes sick, they will have a better chance of a good health outcome.

After screening#

The screening card containing your baby’s blood sample is stored by the laboratory for a period of time. This is in case more testing is needed, and to help the laboratory meet quality standards. You can also choose to make your baby’s screening card available for de-identified health research — for example, to help establish normal values for a new screening test. Such projects require approval by an ethics committee. Access to stored cards is tightly controlled and protected by strict rules.

Support is available#

Genetic support organisations can help people and families affected by genetic conditions to find the information, support and services they need.

If your child has been diagnosed with a genetic condition, it may help to speak to a genetic counsellor. Genetic counsellors are health professionals qualified in both counselling and genetics. As well as providing emotional support, they can help you understand the condition, what causes it, how it is inherited (if it is), and what a diagnosis means for your child’s health and development and for your family. They are trained to give information and support that is sensitive to your family’s circumstances, culture and beliefs.

Key points#

• By the time symptoms of a condition appear, it may already have affected your baby’s development.
• In most cases, affected babies can have treatment to reduce the impact of the condition.
• The heel prick may cause brief discomfort, but holding or feeding your baby during sample collection can help.
• Some conditions, such as hypothyroidism, can cause severe intellectual disability and growth problems if not treated.
• Early detection and treatment help children stay healthy.

Where to get help#