Overview

Hyperthyroidism (overactive thyroid) occurs when your thyroid gland produces too much of the hormone thyroxine. Hyperthyroidism can accelerate your body's metabolism, causing unintentional weight loss and a rapid or irregular heartbeat.

Several treatments are available for hyperthyroidism. Doctors use anti-thyroid medications and radioactive iodine to slow the production of thyroid hormones. Sometimes, hyperthyroidism treatment involves surgery to remove all or part of your thyroid gland.

Although hyperthyroidism can be serious if you ignore it, most people respond well once hyperthyroidism is diagnosed and treated.

Symptoms

Hyperthyroidism can mimic other health problems, which can make it difficult for your doctor to diagnose. It can also cause a wide variety of signs and symptoms, including:

Unintentional weight loss, even when your appetite and food intake stay the same or increase

Rapid heartbeat (tachycardia) — commonly more than 100 beats a minute

Irregular heartbeat (arrhythmia)

Pounding of your heart (palpitations)

Increased appetite

Nervousness, anxiety and irritability

Tremor — usually a fine trembling in your hands and fingers

Sweating

Changes in menstrual patterns

Increased sensitivity to heat

Changes in bowel patterns, especially more frequent bowel movements

An enlarged thyroid gland (goiter), which may appear as a swelling at the base of your neck

Fatigue, muscle weakness

Difficulty sleeping

Skin thinning

Fine, brittle hair

Older adults are more likely to have either no signs or symptoms or subtle ones, such as an increased heart rate, heat intolerance and a tendency to become tired during ordinary activities.

Graves' ophthalmopathy

Sometimes an uncommon problem called Graves' ophthalmopathy may affect your eyes, especially if you smoke. This disorder makes your eyeballs protrude beyond their normal protective orbits when the tissues and muscles behind your eyes swell. Eye problems often improve without treatment.

Signs and symptoms of Graves' ophthalmopathy include:

Dry eyes

Red or swollen eyes

Excessive tearing or discomfort in one or both eyes

Light sensitivity, blurry or double vision, inflammation, or reduced eye movement

Protruding eyeballs

When to see a doctor

If you experience unexplained weight loss, a rapid heartbeat, unusual sweating, swelling at the base of your neck or other signs and symptoms associated with hyperthyroidism, see your doctor. It's important to completely describe the changes you've observed, because many signs and symptoms of hyperthyroidism may be associated with a number of other conditions.

If you've been treated for hyperthyroidism or you currently are being treated, see your doctor regularly as advised so that he or she can monitor your condition.

Causes

Thyroid gland Open pop-up dialog box Close Thyroid gland Thyroid gland Your thyroid gland is located at the base of your neck, just below the Adam's apple.

Hyperthyroidism can be caused by a number of conditions, including Graves' disease, Plummer's disease and thyroiditis.

Your thyroid is a small, butterfly-shaped gland at the base of your neck, just below your Adam's apple. The thyroid gland has an enormous impact on your health. Every aspect of your metabolism is regulated by thyroid hormones.

Your thyroid gland produces two main hormones, thyroxine (T4) and triiodothyronine (T3), that influence every cell in your body. They maintain the rate at which your body uses fats and carbohydrates, help control your body temperature, influence your heart rate, and help regulate the production of protein. Your thyroid also produces a hormone that helps regulate the amount of calcium in your blood (calcitonin).

Reasons for too much thyroxine (T4)

Normally, your thyroid releases the right amount of hormones, but sometimes it produces too much T4. This may occur for a number of reasons, including:

Graves' disease. Graves' disease is an autoimmune disorder in which antibodies produced by your immune system stimulate your thyroid to produce too much T4. It's the most common cause of hyperthyroidism.

Graves' disease is an autoimmune disorder in which antibodies produced by your immune system stimulate your thyroid to produce too much T4. It's the most common cause of hyperthyroidism. Hyperfunctioning thyroid nodules (toxic adenoma, toxic multinodular goiter or Plummer's disease). This form of hyperthyroidism occurs when one or more adenomas of your thyroid produce too much T4. An adenoma is a part of the gland that has walled itself off from the rest of the gland, forming noncancerous (benign) lumps that may cause an enlargement of the thyroid.

This form of hyperthyroidism occurs when one or more adenomas of your thyroid produce too much T4. An adenoma is a part of the gland that has walled itself off from the rest of the gland, forming noncancerous (benign) lumps that may cause an enlargement of the thyroid. Thyroiditis. Sometimes your thyroid gland can become inflamed after pregnancy, due to an autoimmune condition or for unknown reasons. The inflammation can cause excess thyroid hormone stored in the gland to leak into your bloodstream. Some types of thyroiditis may cause pain, while others are painless.

Risk factors

Risk factors for hyperthyroidism, include:

A family history, particularly of Graves' disease

Female sex

A personal history of certain chronic illnesses, such as type 1 diabetes, pernicious anemia and primary adrenal insufficiency

Complications

Hyperthyroidism can lead to a number of complications: