What is congenital hypothyroidism?
This is a disorder affecting the thyroid gland present in neck. The thyroid produces a hormone called thyroxine, which is needed for normal growth and development. If thyroid does not produce enough thyroxine, it causes hypothyroidism. If the
disorder is present at birth, it is called congenital hypothyroidism.
How is congenital hypothyroidism diagnosed?
In most centres in India, babies are tested for congenital hypothyroidism right after birth. If test shows baby has hypothyroidism, it is recommended that they have special scan of neck, this allows doctors to see if your child's thyroid is present and in right place.
What are the symptoms of hypothyroidism?
Most babies are diagnosed early before they have any symptoms, which include feeding difficulties, sleepiness, constipation and jaundice. If congenital hypothyroidism is not diagnosed and treated soon after birth, it can cause problems with mental development and learning, and can lead to clumsiness.
What causes hypothyroidism and is it inhe-rited?
Very early in a baby's development in the uterus, his thyroid gland moves from the back of the tongue to its normal position in the neck. In some babies it does not happen, which means the gland can not work properly, on other occasions the gland does not develop at all. If you have one child with this type of congenital hypothyroidism, the chances of having another baby who is affected is very low.
There is another very rare type of hypothyroidism, in which child thyroid is in right place but cannot produce sufficient thyroxine. This type is inherited, and so there is risk that your second child may have the same condition.
How common is congenital hypothyroidism?
In India, the incidence is 1:3500 to 4000 newborn babies. It is more common in girls than boys, but at moment we do not understand why.
How is congenital hypothyroidism treated?
It is treated by replacing the thyroxine that the body cannot produce. This is usually in tablet form and is given once a day. Although missing a dose will not cause any immediate problems, it is best to try to make sure that your child takes his tablets regularly and therefore keeps a steady level of thyroxine in his blood.
For first couple of years your child will need regular blood tests to check these levels.
Doctors use the information from test to work out the right dose of thyroxine for your child, which changes as they gain weight and develop. Once your child is 2-3 years old will need fewer blood test as the dose is calculated according to how he or she is growing. They will need to take thyroxine tablets for the rest of their life but this quickly becomes routine.
Does the treatment have any side effects?
Because thyroxine tablets are simply replacing a normal chemical produced by the body, giving then the correct dose everyday should not have any side effects.
However if they are given too little thyroxine, your child will develop the symptoms of hypothyroidism mentioned earlier, and over long period grow slower than usual. If your child has too much thyroxine, he will develop mild diarrhoea, not put on weight, and over long period grow more quickly than normal, but as described above the correct dose for your child will be calculated on a regular basis, so these effects are unlikely to occur.
What is the outlook for child with congenital hypothyroidism?
It is very difficult to predict whether any young child will grow up normally. However, screening for hypothyroidism has been going on in India and especially countries like UK and US for long enough to know that almost all children who are diagnosed and treated from early age will grow normally. However, a small proportion of children who have had severe hypothyroidism in the womb may have difficulties later in life, like poor hearing, clumsiness or trouble with learning. The problem is reduced if hypothyroidism is diagnosed early and treated.