Written by Verneda Lights and Matthew Solan | Published on August 15, 2012
Medically Reviewed by George Krucik, MD

What is Hyperthyroidism?

The thyroid gland is a small butterfly-shaped gland located at the front of the neck below your Adam’s apple. It produces tetraiodothyronine (T4) and triiodothyronine (T3), two hormones which control how your cells use energy. The process by which cells use energy is called metabolism.

Hyperthyroidism occurs when too much T4 and/or T3 is produced. Proper diagnosis and treatment of the underlying cause relieves symptoms and prevents complications. Hyperthyroidism can run in families. Make sure to tell your doctor if there is a family history of the condition.

What Causes Hyperthyroidism?

A variety of conditions can cause hyperthyroidism. Graves' disease (an autoimmune disorder) is the most common. It occurs more often in women and tends to run in families. In Graves' disease, antibodies stimulate the thyroid to secrete too much hormone. Other causes of hyperthyroidism include:

  • excess iodine (iodine is needed to make T4 and T3)
  • inflammation of the thyroid gland (thyroiditis causes T4 and T3 to leak out of the gland)
  • tumors of the ovaries or testes
  • benign tumors of the thyroid or pituitary gland
  • taking large amounts of tetraiodothyronine (through dietary supplements or medication)

What are the Symptoms of Hyperthyroidism?

Symptoms are related to the effects of excess thyroid hormone. Thyroid hormones control metabolism, so excessive amounts of T4 or T3 cause a metabolic rate that is too high. This is called a hyper-metabolic state.

People with hyperthyroidism typically have rapid heart rates, weight loss, and heat intolerance. The thyroid gland can be visibly enlarged (goiter). You can also have elevated blood pressure, nervousness, and hand tremors. You may also sweat a lot, feel hungry and restless, and have difficulty concentrating. Your bowel movements may be more frequent and women may have irregular menstrual cycles. In Graves' disease, the eyes may appear quite prominent. This symptom is called exophthalmos. Other symptoms include:

  • weakness
  • irregular heartbeat
  • difficulty sleeping
  • itching
  • hair loss
  • nausea and vomiting
  • breast development in men

Hyperthyroidism can also cause atrial fibrillation, a dangerous arrhythmia that can cause strokes. Congestive heart failure may also occur. Seek medical care immediately if you notice dizziness, shortness of breath, loss of consciousness, or fast irregular heart rate

How is Hyperthyroidism Diagnosed?

The first step is a complete history and physical exam. This can reveal common symptoms, such as weight loss, rapid pulse, elevated blood pressure, protruding eyes, and/or an enlarged thyroid gland (which can either appear either symmetrical or one-sided).

Other tests may be performed to further evaluate your diagnosis. These include:

Cholesterol Level Test

Cholesterol levels vary with the metabolic rate. The metabolic rate is the rate at which cells use energy. In hyperthyroidism, cholesterol can be low due to the elevated metabolic rate.

T4 and T3RU (T3 Resin Uptake)Tests

These tests measure how much thyroid hormone is present in your blood.

TSH Level Test

TSH is a hormone produced by the hypothalamus that stimulates the thyroid gland to produce thyroid hormone. When your thyroid hormone levels are normal or high, TSH should not be elevated.

Triglyceride Level Test

Reasons for low triglyceride levels are the same as for low cholesterol levels.

Thyroid Scan and Uptake

This allows your doctor to see if your thyroid is overactive. It can also tell if the entire thyroid gland or just a single area of the gland is causing the overactivity.


A doctor can use ultrasoung to measure the size of the entire thyroid gland, and any masses within it. An ultrasound allows doctors to know if the mass is solid or cystic.

Computed Tomography (CT) Scan or Magnetic Resonance Imaging (MRI):

A CT or MRI of the head is done if a pituitary tumor is suspected.

Treatment of Hyperthyroidism


Antithyroid medications and radioactive iodine are treatment mainstays. Antithyroid medications inhibit the synthesis of thyroid hormone and radioactive iodine effectively destroys the thyroid producing cells. Methimazole (Tapazole) is an example of an antithyroid medication. However, these medications can have severe side effects, such as low white blood cell count.


Sometimes, a portion or all of your thyroid gland may have to be surgically removed. When this happens, thyroid hormone supplements must be taken to prevent hypothyroidism. Beta-blockers (propranolol) can help to control rapid pulse, sweating, anxiety, and blood pressure. Most people respond well to this treatment. Your doctor may refer you to an endocrinologist, a specialist in hyperthyroidism and other endocrine problems.

Treatment also is important to prevent thyroid storm or thyrotoxicosis and other complications. Thyroid storm is a sudden worsening of symptoms as a result of the release of large amounts of thyroid hormone. It can occur due to stress or infections.

What you can do at Home to Improve Symptoms

Getting the proper amount of calories, calcium, and sodium during and after treatment is important. A diet with too many calories can result in weight gain or obesity. Talk with your doctor and obtain healthy guidelines for your daily diet, nutritional supplements, and exercise.

Hyperthyroidism also can cause your bones to become thin (osteoporosis). Taking vitamin D and calcium supplements during and after treatment can help strengthen your bones.. Make sure to ask your doctor about how much daily vitamin D and calcium is appropriate for you.

Long-Term Outlook for Hyperthyroidism

The long-term outlook depends upon the cause. Some causes go away without treatment. Others, like Graves' disease, get worse over time. Complications of Graves' disease can be life threatening and affect quality of life for a long time.

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