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What is hyperthyroidism?

Hyperthyroidism is a condition that develops when the thyroid gland makes too much thyroid hormone. Thyroid hormones help control body temperature, heart rate, growth, and weight.

What causes hyperthyroidism?

  • An autoimmune disease is an immune system problem that may make your thyroid gland produce too much thyroid hormone. Graves disease is an example of an autoimmune disease that increases thyroid hormone.

  • A family history of thyroid or autoimmune disease can also increase your risk.

  • Certain medicines, such as heart medicines used to help you heart beat normally, can cause hyperthyroidism.

  • Infections near the thyroid gland may damage the gland.

  • Other thyroid problems such as an enlarged or swollen thyroid, lumps caused by infections, or thyroid cancer can affect how your thyroid works.

  • High iodine levels can cause hyperthyroidism. The thyroid gland uses iodine to create thyroid hormone. The thyroid can produce too much hormone if your iodine levels are high.

What are the signs and symptoms of hyperthyroidism?

The signs and symptoms may develop slowly, sometimes over several years:

  • Weight loss, increased appetite, diarrhea, or constipation

  • Increased sweating and heat intolerance

  • Nervousness, restlessness, tremors, and difficulty sleeping

  • Fast heart rate and fast breathing, even at rest

  • Painful lump in your neck or bulging eyes

  • Fatigue and muscle weakness

  • Decreased or absent monthly periods

What is a thyroid storm?

Thyroid storm happens if your thyroid hormone levels get too high. Your temperature may go very high, your heart may beat very fast, and you may have problems thinking. You may have increased sweating, vomiting, or diarrhea. You may have seizures or go into a coma, which can be life-threatening if you do not get medical care quickly. Thyroid storm may happen if you have hyperthyroidism and get an infection or stop taking your thyroid medicine. Injuries, burns, and certain medicines can also cause a thyroid storm.

How is hyperthyroidism diagnosed?

Your caregiver will ask about your symptoms and what medicines you take. He will ask about your medical history and if anyone in your family has thyroid disease. You will have blood tests to check your thyroid hormone level.

How is hyperthyroidism treated?

Treatment will depend on your health, age, and the size of your thyroid gland.

  • Antithyroid medicines decrease thyroid hormone levels. They may also decrease and prevent the signs and symptoms of hyperthyroidism.

  • Radioactive iodine is given to damage or kill some thyroid gland cells. This may decrease the amount of thyroid hormone produced. Tell your caregiver if you know or think you are pregnant. This medicine can be harmful to an unborn baby.

  • Surgery may be done to remove all or part of the thyroid gland.

When should I contact my caregiver?

  • You have a fever.

  • You feel nervous and restless.

  • You have chills, a cough, or feel weak and achy.

  • You run out of thyroid medicine or have stopped taking it.

  • You have questions or concerns about your condition or care.

When should I seek immediate care or call 911?

  • You have sudden chest pain or trouble breathing.

  • Your heart is beating fast.

  • You faint or have a seizure.

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

© 2015 Truven Health Analytics Inc. Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes. All illustrations and images included in CareNotes® are the copyrighted property of A.D.A.M., Inc. or Truven Health Analytics.

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