Information Living with thyroid disorders Hashimoto's thyroiditis FAQs How will I know if my child is on the right dose of levothyroxine?Your child’s symptoms should diminish within three to six months of starting to take levothyroxine. The amount they take may change throughout their life, which is why it is important to have regular blood tests. These measure whether your child has the right levels of Thyroid Stimulating Hormone (TSH) and thyroid hormones in their blood. If your child’s levels are within the reference range, they should no longer have any symptoms of hypothyroidism. However, sometimes children and young people can still feel unwell even when their TSH and thyroid hormone levels are within the reference range. If this is the case, talk to your doctor about adjusting the levothyroxine dose. As long as the TSH remains in the reference range there may be scope to do so. Do not rule out other possible causes of your child’s ill health.The dose of levothyroxine may need to be reduced if your child displays signs of hyperthyroidism – an overactive thyroid.How often will my child have to have blood tests?Once your child’s condition has stabilised they will usually have a blood test every six months until they are 18. After that they will usually be tested once a year.Will my child’s height and weight be affected?Once your child starts taking levothyroxine, their growth and weight will start to be normal and they may also lose weight. Their final height should not be affected as they will effectively ‘catch up’. Final height may only be affected if your child is not diagnosed for many years.Are there any other conditions or diseases my child is likely to have because of Hashimoto’s thyroiditis? What should I be looking for?Although a child with an autoimmune thyroid disorder such as Hashimoto’s thyroiditis is more likely to develop another autoimmune condition than children who do not have an autoimmune thyroid disorder, the risk is very small.It is recognised that thyroid problems often run in families and if family members are unwell they should make an appointment to see their doctor.