What Is Hyperthyroidism?

Hyperthyroidism is a condition that develops due to overactivity of the thyroid gland, resulting in too much thyroid hormone in the bloodstream. The over-secretion of thyroid hormones leads to overactivity of the body's metabolism.

Types of hyperthyroidism

There are several forms of hyperthyroidism, including:

Graves disease (diffuse toxic goiter)

Graves disease is the most common cause of hyperthyroidism. Researchers believe Graves disease is caused by an antibody which stimulates the thyroid too much. This overstimulation causes the excess production of thyroid hormone. Graves disease is categorized as an autoimmune disorder (a dysfunction of the body's immune system). The disease is most common in young to middle-aged women and tends to run in families.

Toxic nodular goiter (multinodular goiter)

Hyperthyroidism caused by toxic nodular goiter is a condition in which one or more nodules of the thyroid becomes overactive. Symptoms of toxic nodular goiter do not include bulging eyes or skin problems, as in Graves disease. The cause of toxic nodular goiter is not known.


Thyroiditis causes temporary hyperthyroidism, usually followed with hypothyroidism, an underactive thyroid, as in Hashimoto's Thyroiditis. In addition, if a person takes too many thyroid hormone tablets, hyperthyroidism will occur. Rarely, a benign pituitary gland tumor may overproduce thyroid-stimulating hormone (TSH), which causes hyperthyroidism.


The following are the most common symptoms and signs of hyperthyroidism. However, each individual may experience symptoms differently. Symptoms may include:

  • Nervousness
  • Irritability
  • Increased perspiration
  • Thinning of the skin
  • Fine, brittle hair
  • Weak muscles, especially in the upper arms and thighs
  • Shaky hands
  • Fast heartbeat
  • High blood pressure
  • Increased bowel movements
  • Weight loss
  • Sleeping difficulty
  • Prominent eyes
  • Sensitivity to bright light
  • Confusion
  • Irregular menstrual cycle
  • Fatigue
  • Goiter (enlargement of the thyroid gland)

The symptoms of hyperthyroidism may resemble other conditions or medical problems. Always consult your physician for a diagnosis.


In addition to a complete medical history and medical examination, diagnostic procedures for hyperthyroidism may include:

  • Hormone testing: Measurement of thyroid hormones and thyroid-stimulating hormone (TSH) levels in the bloodstream
  • Thyroid ultrasound: A test to evaluate the thyroid gland for evidence of any nodules
  • Thyroid scan: A test that uses a radioactive substance to create an image of the thyroid


Treatment for hyperthyroidism is very specific for each patient. The goal of treatment is to restore the thyroid gland to normal function, producing normal levels of thyroid hormone. Specific treatment for hyperthyroidism will be determined by your physician based on:

  • Your age, overall health and medical history
  • Type of hyperthyroidism
  • Extent of the disease
  • Your tolerance for specific medications, procedures or therapies
  • Expectations for the course of the disease
  • Your opinion or preference

Treatment may include:

  • Use of anti-thyroid drugs that help lower the level of thyroid hormones in the blood
  • Use of radioactive iodine, in the form of a pill or liquid, which damages thyroid cells so that production of thyroid hormones is slowed down
  • Surgery to remove all or part of the thyroid
  • Use of beta-blocking agents, which block the action of thyroid hormone on the body, mostly to decrease the rapid heart rate and palpitations
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