Children's Hospital Colorado

Hyperthyroidism in Children

What is hyperthyroidism in children?

Hyperthyroidism happens when a child's thyroid gland makes more thyroid hormone than they need. The thyroid gland is butterfly-shaped and is located in the neck, just below the Adam's apple. Its job is to release thyroid hormone into the blood to control the body's heart rate, temperature and metabolism. An overactive thyroid gland can get big and it may look and feel like a lump in the throat, especially when the child swallows.

When the thyroid gland releases too much hormone, this speeds up a child's metabolism and causes problems such as anxiousness, weight loss and tremors. It can also affect their growth and development. However, pediatric hyperthyroidism is treatable and is rare compared to hypothyroidism. Hypothyroidism happens when the thyroid gland does not produce enough thyroid hormone.

Treatment is important because hyperthyroidism can cause cognitive delay in children under 3 years old, which affects their ability to think and learn. In newborns, it can be life-threatening if it isn't diagnosed soon after birth. Untreated hyperthyroidism can also cause children to grow quickly at first, and then stop growing early. This can cause short stature.

What causes hyperthyroidism in children?

The main causes of pediatric hyperthyroidism include the following:

  • Graves' disease is the most common cause of hyperthyroidism in children. It is an autoimmune disorder that happens when the body's immune system gets confused, and in addition to attacking germs, attacks the thyroid gland. It uses cells called antibodies, which cause the thyroid gland to release extra thyroid hormone. These antibodies may also attack the muscles behind the eyes, which can cause the eyes to bulge. Graves' disease is also called autoimmune hyperthyroidism.
  • Taking too much thyroid hormone medicine can cause hyperthyroidism. For children taking thyroid hormone medicine to treat a low thyroid problem, it is possible to take too much of the medicine and develop hyperthyroidism instead.
  • Taking in too much dietary iodine can also cause hyperthyroidism. Iodine is an important building block for thyroid hormone production, which is why the World Health Organization recommends using iodized salt. However, it is possible to eat too much iodine. This can happen through excessive consumption of iodine-rich foods like seaweed. Taking iodine supplements is the cause of most cases of iodine overdose.
  • Thyroid nodules are growths in the thyroid gland that sometimes produce extra hormones. If we find a nodule in your child's neck, we may recommend a biopsy. This is a procedure in which we remove a small piece of thyroid tissue and look at it under a microscope to check for cancer cells. Thyroid nodules are not usually cancerous, but when they are, we can surgically remove them.
  • Thyroiditis is a condition in which the thyroid gland becomes inflamed and leaks extra hormones into the blood. This is typically a self-limited condition, which means it will stop on its own. A thyroid gland injury or infection can cause thyroiditis, or it can happen in the early stages of autoimmune diseases such as Hashimoto's thyroiditis.
  • Neonatal Graves' disease, while rare, is the most common form of hyperthyroidism in newborns. It happens when a mother with a history of Graves' disease has antibodies that cross the placenta and stimulate the baby’s thyroid gland.

Who gets pediatric hyperthyroidism

Hyperthyroidism is more common in adolescents than in young children. It is also more common in females than in males. Some risk factors include:

  • A personal or family history of thyroid disease or thyroid nodules
  • A personal or family history of autoimmune diseases
  • Trauma to the thyroid gland
  • For newborns: a mother with a history of Graves' disease

What are pediatric hyperthyroidism signs and symptoms?

Common signs and symptoms include:

  • Weight loss
  • Fast or irregular heart rate
  • Raised blood pressure
  • Enlarged thyroid gland at the front of the neck, also called a goiter
  • Tremors
  • Poor heat tolerance and sweating
  • Anxiousness and irritability
  • Hyperactivity or restlessness
  • Difficulty concentrating
  • Trouble sleeping
  • Loose or increased bowel movements (pooping)
  • Fatigue
  • For girls: light, infrequent menstrual periods
  • Increased appetite

Children with Graves' disease may also have redness, pain or bulging in the eyes. This is the hallmark symptom of Graves' eye disease, also known as Graves' ophthalmopathy or thyroid eye disease. Symptoms may also include light sensitivity, dryness and double vision. Treatments are available to manage these symptoms.

Other symptoms may occur if your child experiences a thyroid storm, also called thyrotoxic crisis. This is a rare, but life-threatening condition. It can occur when hyperthyroidism goes untreated or under-treated. Symptoms of a thyroid storm include high fever, fast heart rate, dehydration, confusion/agitation and diarrhea. A thyroid storm requires emergency treatment.

How is pediatric hyperthyroidism diagnosed?

Our team will review your child's symptoms, take their medical history and perform a full physical exam. We will confirm the diagnosis with blood tests to check your child’s thyroid hormone levels and their thyroid-stimulating hormone level. If your child has hyperthyroidism, the tests will likely show a low level of thyroid-stimulating hormone from the brain, and high levels of thyroid hormones T3 and T4 from the thyroid gland.

We may order further tests to find the cause of the hyperthyroidism. These may include blood tests to check for thyroid-stimulating antibodies that can cause Graves' disease. We may also use thyroid imaging to check the function of the thyroid gland. Imaging tests may include a thyroid ultrasound or a radioiodine scan, in which we use a special scanner to detect how radioactive iodine collects in your child's thyroid cells.

How is hyperthyroidism treated in children?

There are three options for pediatric hyperthyroidism treatment.

  • Anti-thyroid medicine called methimazole is given to decrease thyroid hormone levels. We may also use a medicine called a beta-blocker to decrease your child's symptoms until their thyroid levels are closer to the normal range. Anti-thyroid medicine is usually taken for at least two years. Some children may go into remission and be able to end treatment. Remission is when there are no longer any symptoms of hyperthyroidism. Other children will need ongoing treatment. Those who do stop treatment should be monitored, as hyperthyroidism returns in up to 75% of children. There are possible side effects of anti-thyroid medicine, which include skin rash, joint and muscle pain, liver problems and low white blood cell count. Any problems should be checked by your doctor.
  • Radioactive iodine treatment is a way to permanently treat hyperthyroidism. For this therapy, your child will swallow radioactive iodine. This is safe because their thyroid gland absorbs it. This makes their thyroid gland shrink over time, reducing its hormone production. The radioactive iodine does not harm any other body tissues. Your child may then need to take medicine to replace some of their thyroid hormones and prevent symptoms of hypothyroidism. Hypothyroidism happens when thyroid levels are too low, but it is a safer and easier condition to manage. For families looking for permanent hyperthyroidism treatment, radioactive iodine therapy is our preferred choice. Sometimes we need to perform the treatment more than once, and it can worsen eye problems in Graves' disease.
  • Surgery is another option for permanent hyperthyroidism treatment. We can use it to remove part or all of your child's thyroid gland, depending on their needs. This surgery is called a thyroidectomy. After surgery, your child may need to take medicine to replace their thyroid hormones.

What follow-up care is required for pediatric hyperthyroidism?

Following treatment, routine office visits are important to check your child's growth, thyroid hormone levels and any other symptoms. We see most children with hyperthyroidism every 1 to 3 months at first, and then every 3 to 6 months as their thyroid hormone levels stabilize. How often your child will need to visit depends on their specific situation.

Why choose Children's Hospital Colorado for your child's hyperthyroidism treatment?

We understand that your child is unique. We carefully consider their condition in light of their overall health and work with you to determine their best course of treatment.

Our pediatric endocrinologists treat hyperthyroidism in newborns to adolescents. We also coordinate with experts throughout Children's Colorado to provide complete, integrated care for those with multiple or complex conditions.

If your child has Graves' disease, our pediatric ophthalmologists will test them for Graves' eye disease. We work closely with our pediatric hospitalists and intensivists to help your child get better as quickly as possible.

We offer a full range of medical, radiologic and surgical therapies. We also provide nursing and medical support for our patients all day, every day.