Congenital hypothyroidism symptoms

Over half the babies born with congenital hypothyroidism appear completely normal and have no symptoms at all. This is why it is so important that all children are tested at birth. Congenital hypothyroidism is normally diagnosed before a baby shows any definite signs of the condition.

Some babies with congenital hypothyroidism are sleepy and difficult to feed – although lots of babies have these symptoms without being hypothyroid! Other signs may include:

  • constipation
  • low muscle tone (floppiness)
  • cold extremities
  • slow growth

Some hypothyroid babies have prolonged jaundice after birth.

Although some children with congenital hypothyroidism have development problems, the likelihood of long-lasting effects on development is low. If your child is diagnosed with congenital hypothyroidism, the doctor will examine them very carefully to check for any other problems.

Congenital hypothyroidism diagnosis

In the UK babies are checked for hypothyroidism soon after birth. A test is performed when your baby is about a week old under the UK Blood Spot Screening Programme. It is sometimes referred to as the ‘heel prick’ test or ‘Guthrie’ test. A small amount of blood from the baby’s heel is placed on a filter paper and sent to a laboratory for analysis.

If the results show a high Thyroid Stimulating Hormone (TSH) level and a low thyroxine level and your baby is thought to have congenital hypothyroidism you will be contacted before the baby is three weeks old, and referred to a specialist.

Although learning that your baby has a lifelong condition can be a shock, with treatment your baby has every chance of being as healthy and happy as any other child.

Blood spot screening (the ‘heel prick’ or ‘Guthrie’ test)

Newborn blood spot screening identifies babies who may have rare but serious conditions.

All babies in the UK are screened for several rare but serious conditions. These include phenylketonuria, sickle cell disorders, cystic fibrosis, MCADD and congenital hypothyroidism. In some areas babies are also screened for other conditions. Your midwife will be able to give you further information. You will be asked to give your consent to the test.

Most babies will have normal results but if your child is thought to have one of the conditions, they will have further tests to confirm the results.

NHS information on newborn bloodspot screening 

Public Health Wales' information about newborn bloodspot screening programme in accessible formats

Congenital hypothyroidism treatment

If your baby tests positive for hypothyroidism, their condition should be managed by a paediatric endocrinologist or a paediatrician with a special interest in endocrinology. They will immediately treat your baby with levothyroxine, which is synthetic thyroid hormone. This is a replacement for the thyroxine that their body isn’t able to produce naturally. The dose is carefully calculated based on the weight of your baby and will be adjusted regularly as your baby grows. Your baby will be given blood tests every two to three months during the first year of their life and then every four to six months during infancy and childhood, usually until they are 18. These tests will check your child’s levels of thyroid hormone and TSH. The amount of levothyroxine that your child needs to take will be adjusted depending on the results of these tests.

When your child reaches adulthood and their treatment is stable, they'll normally have a blood test once a year and be placed under the care of a GP.

Most children diagnosed at birth will need to take levothyroxine for life. They will be tested regularly as the amount they'll need to take will change as they grow. It's important to monitor your child’s medication as you'll need to make sure that they take it regularly.