Revised 2015

Congenital hypothyroidism is a condition resulting from an absent or under-active thyroid gland or one that cannot make thyroid hormone because of a ‘production line’ problem. The term 'congenital' means that the condition is present at birth. Untreated, it can result in impaired neurological development and a decrease in intelligence quotient (IQ).


Sometimes the thyroid gland

  • Does not develop in the unborn baby
  • Is in the wrong position and does not work well
  • Is in the right position but does not produce thyroxine normally (a ‘production line’ problem)


  • Sleepy and difficult to feed
  • Constipation
  • Cold hands and feet
  • Low muscle tone (floppiness)
  • Poor growth
  • Prolonged jaundice
  • Sometimes symptoms may be very hard to spot


  • All babies born in the UK are screened for congenital hypothyroidism using a heel prick blood test usually performed by midwives about four to five days after birth (called the Guthrie test)


  • Levothyroxine in tablet or liquid form
  • The dose will be adjusted as the child grows
  • It is important to take the tablets regularly and on the same schedule
  • Your baby should be managed by a paediatric endocrinologist or a paediatrician with a special interest in endocrinology

Are there any side effects?

  • Too much levothyroxine may cause irritability, mild diarrhoea, or poor weight gain.
  • Too little levothyroxine over a significant period of time may cause lack of energy, constipation, cold extremities, unexpected weight gain or slow growth


Blood tests are carried out

  • Every one or two months in the first year
  • Every four to six months in infancy and childhood

Long term outlook

  • Levothyroxine will usually be needed for life
  • The vast majority of babies diagnosed and treated from birth will grow up normally

It is well recognised that thyroid problems often run in families and if family members are unwell they should be encouraged to discuss with their own GP whether thyroid testing is warranted.

If you have questions or concerns about your thyroid disorder, you should talk to your doctor or specialist as they will be best placed to advise you. You may also contact the British Thyroid Foundation for further information and support, or if you have any comments about the information contained in this leaflet.

The British Thyroid Foundation
The British Thyroid Foundation is a registered charity: England and Wales No 1006391, Scotland SC046037

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Endorsed by:

The British Thyroid Association - medical professionals encouraging the highest standards in patient care and research

The British Association of Endocrine and Thyroid Surgeons - the representative body of British surgeons who have a specialist interest in surgery of the endocrine glands (thyroid, parathyroid and adrenal)

First issued: 2008
Revised: 2010, 2011, 2015
Our literature is reviewed every two years and revised if necessary.

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