Patient information: Hyperthyroidism (overactive thyroid) (The Basics)
Written by the doctors and editors at UpToDate
The thyroid is a butterfly-shaped gland in the middle of the neck. It sits just below the larynx (voice box). The thyroid makes two hormones, called T3 and T4, which control how the body uses and stores energy. The parathyroid glands are four small glands behind the thyroid. They make a hormone called parathyroid hormone, which helps control the amount of calcium in the blood.
What is hyperthyroidism?
— Hyperthyroidism is a condition that can make you feel shaky, anxious, and tired. It happens when a gland in your neck, called the thyroid gland, makes too much thyroid hormone. This hormone controls how the body uses and stores energy.
Hyperthyroidism is the medical term for when a person makes too much thyroid hormone. People sometimes confuse this condition with Hypothyroidism, which is when a person does not make enough thyroid hormone.
What are the symptoms of hyperthyroidism?
— Some people with hyperthyroidism have no symptoms. When they do occur, symptoms can include:
●Anxiety, irritability, or trouble sleeping
●Weakness (especially in the arms and thighs, which can make it hard to lift heavy things or climb stairs)
●Sweating a lot and having trouble dealing with hot weather
●Fast or uneven heartbeats
●Weight loss even when you are eating normally
●Frequent bowel movements
Hyperthyroidism can also cause a swelling in the neck called a “goiter.” If it is caused by a medical problem called Graves’ disease, the condition can also make the eyes bulge.
Untreated hyperthyroidism can cause a heart rhythm disorder called “atrial fibrillation,” chest pain, and rarely, heart failure.
In women, hyperthyroidism can disrupt monthly periods. It can also make it hard to get pregnant. In men, hyperthyroidism can cause the breasts to grow or lead to sexual problems. These problems go away when hyperthyroidism is treated.
Is there a test for hyperthyroidism?
— Yes. Your doctor can test you for hyperthyroidism using a simple blood test. If the blood test indicates a problem, the doctor might run other tests, too.
How is hyperthyroidism treated?
— Hyperthyroidism can be treated with:
Medicines – Two types of medicines can be used to treat hyperthyroidism:
•Anti-thyroid medicines reduce the amount of hormone your thyroid gland makes.
•Beta-blocker medicines help reduce the symptoms of hyperthyroidism. Beta-blockers can make you more comfortable until the thyroid imbalance is under control.
●Radioactive iodine – Radioactive iodine comes in a pill or liquid you swallow. It destroys much of the thyroid gland. Pregnant women should not use this treatment, because it can damage the baby’s thyroid gland. But the treatment is safe for women who are not pregnant and for men. The amount of radiation used is small. It does not increase the chance of getting cancer, and it does not cause problems getting pregnant in the future or increase the risk of birth defects in future pregnancies.
●Surgery – Doctors can do surgery to remove part or all of the thyroid gland. Doctors do not often recommend surgery, because the other treatment choices are safer and less costly. But surgery is the best choice in some cases.
Most people who are treated with radioactive iodine or who have surgery end up making too little thyroid hormone after treatment. They must take thyroid hormone pills after treatment—for the rest of their life.
What if I want to get pregnant?
— If you take anti-thyroid medicine, talk to your doctor before you start trying to get pregnant. You will probably need to take different medicines at different times in your pregnancy. Plus, your doses might need to be adjusted.
If you were treated with radioactive iodine, wait at least 6 months before you start trying to get pregnant. This will give your doctor enough time to find out if your thyroid is making enough thyroid hormone after the radioactive iodine treatment. If the radioactive iodine caused the thyroid to make too little thyroid hormone, you will need to take thyroid hormone pills. It is important to have a normal amount of thyroid hormone in your body before getting pregnant.
Whatever treatment you use, you should have your thyroid hormone levels checked often during pregnancy. Thyroid hormone levels must be at the right level during pregnancy to avoid risks to both the mother and the baby.