What is hyperthyroidism?

Hyperthyroidism is the medical term for when a person makes too much thyroid hormone.

Hyperthyroidism is a condition that can make you anxious, and tired.

People sometimes confuse this condition with HYPOthyroidism, which is when a person does not make enough thyroid hormone. (see hypothyroidism and thyroid basics)

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)
  • Trembling
  • Sweating a lot and having trouble dealing with hot weather
  • Fast or uneven heartbeats
  • Feeling tired
  • 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.

What are the causes of hyperthyroidism?

Common causes of hyperthyroidism are:


  1. Graves Disease which is an antibody mediated disorder (Autoimmune).
  2. Thyroiditis: This is most commonly due to a viral infection of the thyroid gland which is self limiting.
  3. Toxic multinodular goiter: The entire gland is enlarged irregularly and produces excess hormones.
  4. Hyperfunctioning nodule: A small/large swelling/nodule over produces the hormones.

What tests might be required for diagnosis?

Besides T3T4TSH, a technetium 99m thyroid scan, TRAB levels and ultrasound may be required to clinch the diagnosis and differentiate above mentioned conditions.

How is hyperthyroidism treated?

Hyperthyroidism can be treated with:


  • Medicines– Two types of medicines can be used to treat hyperthyroidism:


Anti-thyroid medicines (carbimazole and propylthyouracil) reduce the amount of hormone your thyroid gland makes.


Beta-blocker medicines like propranolol 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. The treatment is safe for women who are not pregnant and for men. The amount of radiation used is small. 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 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 plan 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. 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.