Health Guide » 
Topic Overview
What is hyperthyroidism?
Hyperthyroidism develops when the thyroid gland produces too much thyroid hormone. Thyroid hormones regulate your metabolism—how your body burns calories to produce energy—and influence all of your body processes, including heart rate, digestion, muscle and bone strength, and cholesterol levels.
See an illustration of the thyroid gland.
What causes hyperthyroidism?
Graves' disease, also known in Europe as von Basedow's disease, is the most common cause of hyperthyroidism. Other causes include thyroid nodules—growths in the thyroid gland—and thyroiditis, inflammation of the thyroid gland.
This topic focuses on the diagnosis and treatment of hyperthyroidism caused by Graves' disease.
What are the symptoms of hyperthyroidism?
The most common symptoms of hyperthyroidism include:
- Nervousness, mood changes, weakness, and fatigue.
- Hand tremors; a rapid, pounding, and irregular heartbeat; and shortness of breath, even when resting.
- Excessive sweating, and warm, flushed skin that may be itchy.
- An increased number of soft stools.
- Fine, soft hair and hair loss.
- Loss of appetite.
- Weight loss.
Hyperthyroidism symptoms vary by age. For example, children may have rapid growth with faster-than-expected bone maturation, while older adults may have a decreased appetite, weight loss, and atrial fibrillation. The severity of symptoms may also vary, and depression and fatigue may occur (apathetic hyperthyroidism).
How is hyperthyroidism diagnosed?
Hyperthyroidism is diagnosed through a medical history, a physical exam, and blood tests that check your levels of thyroid hormones.
How is hyperthyroidism treated?
Treatment options for hyperthyroidism include antithyroid medication, radioactive iodine, and surgery. In most cases, one or more of these treatments reduce or eliminate symptoms. Because hyperthyroidism may return after successful treatment, it is important that your thyroid hormone levels be checked regularly.
Left untreated, hyperthyroidism can lead to atrial fibrillation, osteoporosis, and a life-threatening condition called thyroid storm.
