Hyperthyroidism (overactive thyroid) is a condition in which the thyroid gland produces excessive amounts of thyroid hormone. Hyperthyroidism can accelerate the body's metabolism, leading to weight loss, rapid heartbeat, sweating, and nervousness. Because thyroid hormone affects the body’s metabolism, it’s important to seek treatment. Untreated hyperthyroidism can lead to serious health problems, such as heart arrhythmias, osteoporosis and eye problems.

Causes and Risk Factors of Hyperthyroidism

The most common cause of hyperthyroidism is Graves’ disease – an autoimmune disorder in which the immune system stimulates the thyroid to overproduce thyroid hormones. In addition to hyperthyroidism, Graves’ disease can be associated with thyroid eye disease symptoms, such as swelling, dryness, and bulging of the eyes.

Two other common causes of hyperthyroidism include:

Hyperfunctioning thyroid nodules. This type of hyperthyroidism occurs when one or more thyroid nodules (or lumps) cause the thyroid to produce excessive amounts of thyroid hormone.

Thyroiditis. Inflammation of the thyroid gland (called thyroiditis) usually occurs after a viral infection and cause the thyroid gland to become inflamed and produce excessive thyroid hormone.

There are also several risk factors that can increase an individual’s chances of developing hyperthyroidism, including:

• Female gender

• Older than age 60

• A family history of thyroid disease

• Autoimmune disease, such as type 1 diabetes

• Pituitary gland problems

• Overconsumption of iodine (either from foods or supplements)

• Iodine containing medications (such as amiodarone)

• Being pregnant

• Being postpartum

If you have a number of risk factors for hyperthyroidism, speak with your physician about whether thyroid screening may be appropriate for you.

Symptoms of Hyperthyroidism

Hyperthyroidism can cause a wide variety of symptoms, which vary based on how long the thyroid gland has been producing too much thyroid hormone. Some of the most common symptoms include:

• Sudden weight loss

• Rapid heartbeat, irregular heartbeat or pounding of the heart

• Nervousness, anxiety or irritability

• Tremors (trembling of the hands and fingers)

• Changes in menstrual patterns (usually shorter cycles, with lighter flow)

• Increased appetite

• Increased sensitivity to heat

• Increased perspiration

• Increased frequency of bowel movements

• An enlarged thyroid gland (goiter)

• Fatigue

• Muscle weakness

• Difficulty sleeping (insomnia)

• Hair loss

Older adults may have subtle symptoms, such as increased heart rate, increased perspiration and a tendency to become more tired during normal activities. If the patient is diagnosed with Graves’ disease, Graves' ophthalmopathy (eye disease) may occur, especially in individuals who smoke.

Graves' ophthalmopathy can cause the muscles behind the eyes to swell, which often results in the eyes bulging out of their normal position. This condition may also result in dry, red and swollen eyes, as well as excessive tearing or discomfort, sensitivity to light, blurry or double vision, and decreased eye movement.

If you have symptoms of hyperthyroidism, it’s important to speak to your physician about thyroid screening. Be sure to also discuss all medications you are taking, since certain medications like beta blockers can mask many of the signs of hyperthyroidism.

Diagnosing Hyperthyroidism

If you have symptoms of hyperthyroidism, your physician will start the diagnostic process by reviewing your medical and family history, risk factors, and performing a physical exam to check your thyroid gland.

Your physician will also order blood tests to measure levels of thyroid stimulating hormone (TSH) and other thyroid hormones. A high level of thyroid hormone in the blood, plus a low level of TSH is common with an overactive thyroid gland. In addition, if Graves’ disease is suspected, your physician may order blood tests to check your thyroid antibody levels (TSIg).

If blood tests show that your thyroid is overactive, your physician may order one or more of the following tests to help determine why your thyroid is overactive:

Thyroid scan. A thyroid scan is a nuclear medicine imaging study that uses a radioactive iodine tracer to reveal if the thyroid gland is overactive (which indicates Graves’ disease) or whether you have a toxic nodule (overactive thyroid nodule) or thyroiditis (thyroid inflammation).

Radioactive iodine uptake test. This test is another type of nuclear medicine imaging study that measures the thyroid gland’s ability to absorb iodine. A high uptake of radioiodine indicates either Graves' disease, or hyperfunctioning nodules. If radioiodine uptake is low, this indicates thyroiditis as the cause of hyperthyroidism.

Proper diagnosis is important since knowing what's causing your hyperthyroidism will help your physician plan the right treatment protocol personalized for you. At Hoag, our multidisciplinary team of thyroid care experts are highly skilled in the diagnosis and treatment of thyroid disease.

Treatment Options for Hyperthyroidism

There are several treatments for hyperthyroidism. The most effective therapy for you depends on your age, physical condition, the underlying cause of your hyperthyroidism, personal preference and the severity of your disorder. In determining which treatment is best for you, your doctor will also take your medical history, physical examination, and any diagnostic tests into consideration.

The following are the most common treatments for hyperthyroidism:

Radioactive iodine therapy. Radioactive iodine is absorbed by the thyroid gland causing the level of thyroid hormone in the body to decrease and symptoms to subside, usually within three to six months. Because this treatment usually results in permanent low thyroid (hypothyroidism), you may eventually need to take lifelong daily medication to replace thyroid hormones.

Anti-thyroid medications. These medications do not cause permanent damage to the thyroid gland, and gradually reduce symptoms of hyperthyroidism by preventing the thyroid gland from producing excess amounts of hormones. Treatment with anti-thyroid medications typically lasts a year or longer (and will need to be gradually tapered off). For some individuals, this resolves hyperthyroidism permanently, and patients can go into remission. However in others, it may result in a recurrence of Grave’s disease. For patients with toxic nodular, or multinodular goiter, anti-thyroid medications may be used in preparation for radioiodine treatment, or surgery. However, anti-thyroid medications are not usually used for a prolonged a period to treat toxic thyroid nodules due to potential adverse side effects.

Beta blockers. These medications can be helpful in slowing down your heart rate and reducing the symptoms of palpitations, tremors, and nervousness. For that reason, your physician may prescribe beta blockers to help you feel better until your thyroid hormone levels are closer to normal.

Surgery. The total or partial surgical removal of the thyroid is called a thyroidectomy. When performed by an experienced endocrine surgeon, thyroidectomy is an effective treatment. Surgery may be recommended for certain types of hyperthyroidism, such as Graves' disease and nodular thyroid goiters for patients who have symptoms such as difficulty breathing or swallowing. As with radioactive iodine, thyroid hormone replacement therapy is usually necessary after surgery in order to supply your body with a balanced level of thyroid hormones. As with any surgical procedure, thyroidectomy poses some small risks, including potential damage to the vocal cords and parathyroid glands, which is why it’s important to seek care from an experienced endocrine surgeon utilizing the latest advances in thyroid surgery.

In addition, if Graves' disease is affecting your eyes (Graves' ophthalmopathy), your physician may recommend treatment with corticosteroids to reduce swelling behind your eyes. In severe cases, surgery may be recommended.

When discussing with your physician which treatment option is best for you, make sure you understand the risks, benefits, and side effects of treatment. The ultimate goal in treating hyperthyroidism is to determine the best option for lowering thyroid hormone levels to achieve a healthy balance, which is essential to your body's ability to function at its best.