About congenital hypothyroidism

Heel prick test for CHT
on Thu 28 Jan


Commonly referred to as CHT, congenital hypothyroidism is found present in one out of every 3,500 to 4,000 new-born babies and it’s twice as common in girls as boys.


80% of babies who have CHT have no thyroid; or one that is severely reduced in size; or a thyroid which is abnormally located. This has happened during their development in the womb and the risk to parents of such a baby having a second child with the same problem is low - provided they have sufficient iodine in their diet. Lack of iodine is the most common cause of CHT worldwide.



20% of babies with CHT have developed a thyroid gland but it is not functioning. Unfortunately this is an inherited risk and so subsequent children may also be affected.


In nearly all of the developed world congenital hypothyroidism is tested for as part of a new-born screening programme.  In the UK this is usually when babies are between 5 and 8 days old and this is done by means of the heel prick test (sometimes called a Guthrie test)


This level of screening is essential because more than 50% of babies born with the condition look entirely normal and display no symptoms. Other babies with CHT may display some of the following:


  • Excessive sleeping
  • Reduced interest in feeding
  • A low or hoarse cry
  • Constipation
  • Floppiness due to low muscle tone
  • Cold hands and feet
  • Poor growth
  • Prolonged jaundice


If the test indicates that a baby has possible CHT, a second test will be given and then a scan of the neck will be done.


Left untreated CHT can cause impaired brain development leading to poor hearing; clumsiness or challenges with learning, and slow growth.  However, if thyroid hormone treatment is started before the baby is two to three weeks old a decrease in IQ can usually be avoided. Babies found to test positive for this condition are usually referred to an endocrinologist with a special interest in paediatrics or a paediatrician with a special interest in endocrinology.


Levothyroxine will be prescribed according to the baby’s weight and regular tests will be taken to ensure the accurate adjusting of the dosage as the baby grows. Blood tests are usually taken every few weeks during the first 12 months of the child’s life; every three to six months until adulthood and then every 6 to 12 months as an adult.


It’s possible to crush Levothyroxine and give it in liquid but if bottle feeding it’s recommended to do this via a spoon or pipette in case the baby doesn’t finish the bottle in which the tablet has been crushed. It’s also advisable to avoid giving the baby a full feed after the Levothyroxine in case the baby vomits and loses part of the dose.


Children with CHT will be on Levothyroxine for life but this should not be a cause for concern as the tablets are simply replacing the thyroxine which is not being produced. Levothyroxine lasts in the body for several days so a missed dose is not disastrous in itself - however it’s important to get into the habit of regular daily medication.


Levothyroxine is currently free of prescription charges so do check that the corresponding prescription is exempt from costs.


Although every effort is made to ensure that all health advice on this website is accurate and up to date it is for information purposes and should not replace a visit to your doctor or health care professional.


As the advice is general in nature rather than specific to individuals Dr Vanderpump cannot accept any liability for actions arising from its use nor can he be held responsible for the content of any pages referenced by an external link



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