Hypothyroidism in children Dr Trisha Macnair A child may be born with hypothyroidism or may develop the condition at any time.

In this article

What is hypothyroidism? Symptoms

Causes and risk factors Treatment and recovery

Hypothyroidism is underactivity of the thyroid gland - an important gland found in the neck that produces two hormones called T3 and T4 (thyroxine), which control the metabolic rate of many tissues. In hypothyroidism, levels of these hormones are lower than normal.

Symptoms of congenital hypothyroidism, which appear from birth, include failure to thrive, feeding problems, prolonged jaundice, constipation, pale cold dry skin, large tongue, hoarse cry, goitre (rare), umbilical hernia, delayed development and an unusual facial appearance.

In acquired hypothyroidism there may be short stature, dislike of the cold, thin dry hair, slow pulse, pale puffy eyes with loss of eyebrows, goitre, constipation, slow reflexes, obesity, delayed puberty, deterioration in school work, depression and learning difficulties.

There are several causes of congenital hypothyroidism. These include:

• Abnormalities in the development of the thyroid gland while the baby is in the womb
• Genetic abnormalities that interfere with thyroid hormone production
• Iodine deficiency (the most common worldwide cause but rare in the UK)
• Problems with the pituitary gland (which regulates the thyroid gland)

Acquired hypothyroidism in children is most often caused by an autoimmune disease in which the immune system attacks the gland, sometimes after a viral infection.

Children with acquired hypothyroidism may have other autoimmune disorders including diabetes mellitus. Both are more common in children with Down's syndrome or Turner syndrome. It's more common in girls than in boys.

Congenital hypothyroidism is one of the few preventable causes of severe learning difficulties. One in 4,000 babies is born with congenital hypothyroidism. In about five per cent of cases, there's a genetic dysfunction in hormone production.

The condition is screened for as part of the Newborn Blood Spot Screening Programme which operates throughout the UK. Between day five and eight of life (ideally on day five, with the date of birth counting as day 0) a sample of blood is taken from the baby by pricking their heel. This blood is collected as a spot on a special card which is sent to the laboratory to test for several of the more common inherited conditions, including congenital hypothyroidism.

If the condition is detected, treatment can then be started soon after birth before symptoms develop. So through screening, early diagnosis and treatment can prevent learning difficultiesHypothyroidism is easily treated with replacement thyroid hormone called thyroxine. This can be in tablet or liquid form but must be taken for life. The dose needs to be checked regularly and adjusted if necessary.

When iodine deficiency is the cause, iodine supplements may be all that are needed.

This article was last medically reviewed by Dr Trisha Macnair in May 2009.