Your child should be referred to a paediatric endocrinologist or a paediatrician with a special interest in endocrinology. who will start them on treatment with levothyroxine. Your child will need to take levothyroxine for life. Levothyroxine is a replacement for the thyroxine that their body should produce naturally. The dose will be calculated based on the weight and age of your child, and may be adjusted as they grow. They will need to have regular blood tests to make sure that they are given the right amount of levothyroxine. This will vary depending on the child’s age and how they are developing – for example a very young child may be tested every six weeks until their thyroid levels are stable. An older child who is growing at a normal rate and feeling well may only need to be seen every four to six months. When your child reaches adulthood and their treatment is stable, they will normally have a blood test once a year and be placed under the care of a GP.

Your child’s symptoms should diminish and disappear within three to six months of starting treatment with levothyroxine. In some cases, it may take longer to find the right level. If symptoms return you should arrange to see your child’s GP. It is important to monitor your child’s medication as you will need to make sure that they take it regularly.