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OVERVIEW

What is hyperthyroidism?

Hyperthyroidism, or overactive thyroid disease, means your thyroid gland makes and releases too much thyroid hormone. The thyroid gland is located in the front of your neck, just below your Adam’s apple. It makes hormones that control your metabolism. Metabolism is the pace of your body’s processes and includes things like your heart rate and how quickly you burn calories.

Hyperthyroidism can affect your metabolism. It can also cause nervousness, increased perspiration (sweatiness), rapid heartbeat, hand tremors, difficulty sleeping and weight loss.

SYMPTOMS

What are the symptoms of hyperthyroidism?

Hyperthyroidism usually begins slowly, so its symptoms can be mistaken for stress or other health problems. It can cause a variety of symptoms, including:

• 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 lighter flow, less frequent periods) in women
• Increased sensitivity to heat
• Increased perspiration
• Changes in bowel patterns
• An enlarged thyroid gland (called a goiter), which can appear as a swelling at the base of the neck
• Fatigue
• Muscle weakness
• Difficulty sleeping
• Increased appetite

Older adults may have subtle symptoms, such as increased heart rate, increased perspiration and a tendency to become more tired during normal activities.

If your hyperthyroidism is caused by Graves’ disease, you may also have Graves’ opthalmopathy, a disorder that affects your eyes. These symptoms may show up before, after or at the same time as your symptoms of hyperthyroidism. In Graves’ opthalmopathy, the muscles behind the eyes swell and push the eyeballs forward. Often, the eyeballs will actually bulge out of their normal position. The front surfaces of the eyeballs become can dry, red and swollen. You may notice excessive tearing or discomfort in your eyes, sensitivity to light, blurry or double vision, and less eye movement.

CAUSES & RISK FACTORS

What causes hyperthyroidism?

Grave’s disease is by far the most common cause of hyperthyroidism in Canada. Normally, antibodies produced by the immune system help protect the body against viruses, bacteria and other foreign substances. An autoimmune disease is when your immune system produces antibodies that attack your body’s tissues and/or organs. With Graves’ disease, antibodies produced by the immune system stimulate the thyroid, making it produce too much hormone. Healthcare providers think Graves’ disease may run in families. It is most common among young women.

Two other common causes for hyperthyroidism include:

• Hyper functioning thyroid nodules. One or more nodules or lumps in the thyroid grow and increase their activity so that they make too much hormone.
• A problem with the immune system or a viral infection causes the thyroid gland to become inflamed and produce extra thyroid hormone that leaks into the bloodstream.

DIAGNOSIS & TESTS

How will my healthcare provider know if I have hyperthyroidism?

If you have symptoms of an overactive thyroid, your healthcare provider will check for an enlarged thyroid gland, rapid pulse, moist skin, eye changes and a slight tremor in your fingers or hand. The diagnosis can be confirmed with blood tests that measure the amount of thyroid hormone in your blood.

If your blood tests show an overactive thyroid, your healthcare provider may do a thyroid scan to see if your entire thyroid is affected (which indicates Graves’ disease) or if you have hyper functioning thyroid nodules or thyroiditis.

Your healthcare provider may also do a radioactive iodine scan, TSH receptor antibody measurement, or thyroid ultrasound to help distinguish Graves’ disease from other conditions and may be ordered depending on the specific situation.

TREATMENT

How is hyperthyroidism treated?

There are several treatments for hyperthyroidism. Your healthcare provider will choose an appropriate treatment based on your age, your physical condition, the cause of your hyperthyroidism and how severe your condition is.

• Radioactive iodine. Radioactive iodine is taken by mouth. It gets into the blood stream and is absorbed by overactive thyroid cells. Radioactive iodine causes the level of thyroid hormone in the body to decrease. Symptoms usually subside in 3 to 6 months. Permanent low thyroid activity (hypothyroidism) usually is the final result, but this can be treated with thyroid supplements. Despite concerns about radioactive material, this treatment has been used for more than 60 years without causing any problems.
• Anti-thyroid medicine. These drugs treat hyperthyroidism by blocking the thyroid’s ability to produce hormones. Symptoms begin to improve in 6 to 12 weeks but treatment usually continues for at least a year.
• Hyperthyroidism can be treated with a surgery (called a thyroidectomy) in which your healthcare provider removes most of your thyroid gland. After surgery, you will likely develop hypothyroidism (underactive thyroid disease). You will then need to take a thyroid hormone supplement to restore your hormone levels to normal.
• Beta blockers. No matter what other method of treatment you use, your physician may prescribe a beta blocker drug to slow your heart rate and reduce palpitations, shaking and nervousness until your thyroid levels are closer to normal.

COMPLICATIONS

Are there any complications I should know about?

If it is not treated, hyperthyroidism can lead to other health problems. They include:

• Heart problems. A rapid heart rate, a heart rhythm disorder (called atrial fibrillation) or congestive heart failure can result.
• Brittle bones (osteoporosis). Too much thyroid hormone can interfere with your body’s ability to incorporate calcium into your bones. Be sure to get enough calcium in your diet to prevent osteoporosis.
• Eye problems due to Graves’ opthalmopathy. To relieve the symptoms of Graves’ opthalmopathy:
• Apply cool compresses to your eyes
• Wear sunglasses
• Use lubricating eyedrops
• Elevate the head of your bed to reduce blood flow to your head
• Red, swollen skin on the shins and feet due to Graves’ disease. Try using over-the-counter creams containing hydrocortisone for relief.
• Thyrotoxic crisis. A sudden worsening of hyperthyroidism symptoms that leads to a fever, rapid pulse and even delirium (symptoms of which can include decreased awareness and mental clarity, restlessness and agitation). See a healthcare provider right away if this occurs.

QUESTIONS TO ASK YOUR HEALTHCARE PROVIDER

• What is the likely cause of my hyperthyroidism?
• Do I have Graves’ disease?
• What are the results of my blood test(s)? What do these results mean?
• What is the best treatment option? Will I need medicine? For how long?
• Will I need surgery?
• What risks are associated with these treatment options?
• When can I expect relief from my symptoms?
• Am I at risk for any complications? What can I do to minimize the risk of complications?

FOR MORE INFORMATION

Thyroid Foundation of Canada
http://www.thyroid.ca/

Sources

Hyperthyroidism: Diagnosis and Treatment by JR Reid, M.D., and SF Wheeler, M.D. (08/15/05, http://www.aafp.org/afp/20050815/623.html)