NHS Newborn Blood Spot Screening Programme

Congenital hypothyroidism and your child

Public Health England leads the NHS Screening Programmes

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Congenital hypothyroidism and your child

Congenital hypothyroidism About 1 in 3,000 babies born in the UK has congenital hypothyroidism (CHT). Congenital means the baby is born with the condition.

Babies with CHT do not make enough of the hormone thyroxine, an important chemical made in the body. Thyroxine is produced by a gland in the neck called the thyroid. The thyroid gland usually starts working in the unborn baby when the mother is about 20 weeks pregnant.

Without thyroxine, babies do not grow properly and can develop permanent physical and mental disabilities. CHT cannot be cured but can be treated simply and successfully.

Newborn blood spot screening is vital because it helps identify babies with CHT before they start to show symptoms. A few babies born with CHT may have symptoms such as jaundice, dry skin, puffy eyelids, a large tongue, a hoarse cry, feeding problems, constipation and sleepiness.

There is currently no reliable way to detect CHT before birth and no way to prevent babies being born with CHT.

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Causes and types of CHTIn most cases CHT happens by chance and the specific cause is not known. There is nothing the parents of a baby with CHT could have done to prevent it.

Babies may develop CHT for different reasons.

1. Abnormal development of the thyroid gland

The thyroid gland may not reach its proper place in the neck during development in the womb, or it may be too small or even missing completely. There is usually no family history of CHT in these babies. The chance of a parent having another baby with CHT is very low.

2. Thyroid gland does not make thyroxine

In 10 to 20% of babies with CHT the thyroid gland is in the normal place and might even be enlarged, but it still does not produce enough thyroxine. In these families, there may be other relatives with thyroid conditions and there is a chance of having another baby with CHT. If you plan to have more children you may wish to discuss this with your healthcare team.

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Congenital hypothyroidism and your child

Living with CHTChildren with CHT are able to live full and active lives, like other children, as long as treatment is taken every day. A few children may develop problems with learning and clumsiness, and may need extra help. There may be a slightly increased risk of hearing problems, so talk to your healthcare team if you have any concerns about your child’s hearing.

Your child should have all the usual immunisations or medical treatment needed for other conditions. They do not need to eat any special diet because of CHT. If you have any other concerns about your baby’s health, please ask your healthcare team.

Diagnosis of CHT CHT is diagnosed by measuring the levels of free thyroxine (free T4) and thyroid stimulating hormone (TSH) in the baby’s blood. Some babies will also have a scan of the neck to look at the thyroid gland.

Newborn blood spot (‘heel prick test’)

The newborn blood spot screening test measures the level of TSH in the baby’s blood. TSH triggers the thyroid gland to make more thyroxine. A high level of TSH suggests the thyroid is not working properly to make enough thyroxine. More blood tests may be needed.

Other blood tests

A repeat blood test is done to check the results of the newborn blood spot screening test. This measures the level of TSH again

Congenital hypothyroidism and your child

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and also the level of free T4 in the blood. A high level of TSH together with a low level of free T4 helps to confirm the diagnosis of CHT.

Thyroid scans

A thyroid scan may be recommended. Thyroid scans are very safe and can give information about the type of CHT and whether this is likely to be permanent. They can help find out whether there is a chance of CHT occurring in future children.

There are 2 different types of thyroid scan:

Thyroid uptake scan

This test can provide a picture of the thyroid gland and can help see how it is working. A small dose of a chemical (radioiodine or technetium) is injected into the blood before a scan of the neck is done. An active thyroid gland takes up the chemical and its position can be seen on the scan. An underactive thyroid may not take up much chemical.

Ultrasound scan of the neck

This is to look at the thyroid position, shape and size. No injection is required and this is completely pain-free.

Tests for the mother

The baby’s mother may also have some blood tests to aid diagnosis.

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Congenital hypothyroidism and your child

TreatmentThe treatment for CHT is to take levothyroxine by mouth once a day. This replaces the thyroxine the body cannot make. Babies should start treatment promptly during the first few weeks after birth. Most children will need to continue it throughout life. Studies of children taking levothyroxine show this treatment is safe and effective because it puts back what the body isn’t making properly.

How do I give levothyroxine?

It is very important for your baby to begin taking levothyroxine as soon as possible and to continue to take it for as long as your healthcare team advises. In some babies it may be possible to discontinue levothyroxine after 2 to 3 years if tests show it is not needed. Most babies with CHT take levothyroxine for life.

Levothyroxine should be given every day by mouth. It is available in tablets or a solution and is prescribed in an amount measured in ‘micrograms’. As levothyroxine is simply replacing a normal body chemical, giving the correct dose every day should not have any side effects.

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Tablets

Thyroxine tablets are small and tasteless. For very young babies, the tablets can be crushed and dissolved in a little breast milk, formula milk or water. This can be given from a small syringe or a spoon. Most babies accept the medication quite easily in this way.

Solution

Levothyroxine may be prescribed as an oral solution. This comes in different strengths so it is important to make sure you are given the correct one when collecting a new supply. The solution can be given in the same way as a crushed tablet, using a syringe or a spoon.

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Congenital hypothyroidism and your child

Important things to remember about giving levothyroxine

1. Tablets should not be mixed into a bottle feed because if the baby does not finish the bottle, he or she will not receive the full dose.

2. If you forget a dose of thyroxine give it as soon as you remember. Do not give a double dose.

3. If your baby vomits immediately after taking the tablet, you will need to give another dose.

4. A suspension is not the same as a solution. Do not use a suspension. If you are in doubt, please speak to a healthcare professional.

5. Older babies can have their tablets crushed into a spoonful of cereal, mashed vegetables or fruit.

6. Certain foods such as soya products and iron medications may alter the amount of thyroxine that gets into the blood. Check with your healthcare team if you are unsure about anything you are giving your baby.

7. Talk to your healthcare team about how to manage your baby’s thyroxine treatment in special situations, for example if your baby is ill.

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Follow-up checksYour baby will need regular blood tests to make sure they receive the correct dose of levothyroxine for their age and size. The dose will be increased over time, as your baby grows up and several dose changes will be needed.

The first blood tests are usually 2 weeks after treatment starts and then after 4 weeks, 8 weeks and 3 months. They are then every 3 months until the baby is a year old. Blood tests will be needed more frequently during the first year of life as your baby will be growing fast. Testing then tends to be less frequent in the next 2 years but should not be less than twice a year.

The healthcare team will also carefully monitor your child’s growth.

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Congenital hypothyroidism and your child

Useful termsAgenesisThe complete absence of the thyroid gland.

CongenitalCongenital means the baby is born with the condition.

Congenital hyroidism (CHT)A condition where, for one of a number of reasons, the thyroid gland does not work properly and fails to make the thyroid hormone called thyroxine

DyshormonogenesisThe thyroid gland is of normal size and position, or may even be enlarged, but still does not produce enough thyroxine.

DysgenesisThe thyroid gland is missing, ectopic (in the wrong place) or underdeveloped (small).

EndocrinologyA branch of medicine dealing with disorders of the glands and hormones of the body such as CHT.

Ectopic thyroidThe thyroid gland is in the wrong place or position.

HypothyroidismBabies with hypothyroidism do not make enough of the hormone thyroxine, a natural chemical made in the body.

LevothyroxineThe full name for the medication given to babies with CHT. Levothyroxine medicine is sometimes just called thyroxine. It replaces the thyroxine that the body cannot produce.

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Paediatric endocrinologistA doctor who specialises in treating endocrine (hormone) disorders in children, such as CHT.

RadioiodineA form of iodine (a chemical) that has a very small amount of radioactivity. It is used for thyroid uptake scans.

Sporadic CHTWhen CHT occurs by chance in babies with no CHT in their family.

T4 (free T4)A measure of the level of thyroxine (or free thyroxine) in the blood. T4 levels are lower than they should be in children with CHT who need treatment.

TechnetiumA chemical with a very small amount of radioactivity used for thyroid uptake scans.

Thyroid uptake scansA safe test to help get a good picture of the thyroid gland and look at its activity. A small dose of a chemical (radioiodine or technetium) is injected into the blood before a scan of the neck is done.

ThyroxineThe thyroid hormone (a special body chemical) produced by the thyroid gland. Children with CHT take a thyroxine or levothyroxine tablet or liquid solution once a day by mouth. This replaces the thyroxine that the body cannot produce.

TSHThyroid stimulating hormone (TSH) is produced by the body to tell the thyroid gland how much thyroxine to make. In children with CHT who are not getting the right treatment, TSH levels in the blood are higher than normal.

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Congenital hypothyroidism and your child

More information about screening: www.nhs.uk

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Front cover image: Shutterstock (KieferPix)

PHE publications gateway number: 2018014

First published: 2007

Updated: April 2018

Review due: 2021

Leaflet reference: NBS06

© Crown copyright 2018

More informationBritish Thyroid Foundation:

• www.btf-thyroid.org

The Child Growth Foundation:

• www.childgrowthfoundation.org

British Society for Paediatric Endocrinology and Diabetes:

• www.bsped.org.uk

NHS Choices:

• www.nhs.uk/bloodspot

Find out how Public Health England and the NHS use and protect your screening information at www.gov.uk/phe/screening-data.