Hyperthyroidism happens when the thyroid gland sends too much thyroid hormone into the bloodstream. The thyroid is a small gland in the neck. It makes hormones that help the body do things like turn food into energy and help kids grow into adults. 

The most common cause of hyperthyroidism is Graves' disease. In Graves' disease, the body's immune system (germ-fighting system) causes the thyroid gland to make too much thyroid hormone. Hyperthyroidism can cause tremors (light shaking), sweating, a fast heartbeat, weight loss, and bulging eyes. Your health care provider prescribed anti-thyroid medicine to lower the amount of thyroid hormone your child's body makes.

• Give your child any prescribed medicines as directed. 
• Make sure your child goes to all follow-up visits. 
• Have your child get all the tests the health care provider ordered.
• Pay attention to your child's weight.

Your child:

• gets a rash or hives after starting an anti-thyroid medicine called methimazole
• develops a fever or a sore throat
• has heart palpitations (feeling that the heart is skipping a beat or a pounding heartbeat)
• has trouble sleeping
• continues to lose weight
• is having mood swings
• doesn't take the medicine as instructed

Your child:

• has trouble breathing
• has a racing heartbeat that lasts

Can kids have other symptoms of hyperthyroidism? Yes, another symptom in kids with Graves' disease is swelling of the thyroid gland. The swelling can be felt as a lump under the skin at the front of the neck. When it is large enough to see easily, it's called a goiter.

What if my child's hyperthyroidism doesn't get better? If your child still has hyperthyroidism after a few years of taking medicine or has problems taking the medicine, your health care provider may consider other treatments. Options include surgery and treatment with radioactive iodine. 

How does radioactive iodine (RAI) work? RAI damages the thyroid gland so that it can't make too much thyroid hormone. This doesn't harm other parts of the body. The thyroid gland quickly absorbs the RAI from the bloodstream and, within a few months, the gland shrinks and symptoms slowly disappear.

Why would a child still lose weight while on treatment? Some kids, especially teenage girls, may still lose weight because they avoid taking their medicines. They like the weight loss that happens with hyperthyroidism. Losing weight like this can cause serious health problems. Contact your doctor if this is a concern.