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OVERVIEW

What is hyperthyroidism?

Hyperthyroidism is known as overactive thyroid.  It occurs when your thyroid gland makes and releases too much thyroid hormone. The thyroid gland is shaped like a butterfly. It is in the front of your neck, below your Adam’s apple. The thyroid makes hormones that control your metabolism. The thyroid makes hormones that control your body’s metabolism. It affects your heart rate and the function of your other organs. It also affects your muscles, bones, and menstrual cycles.

 Hyperthyroidism can be related to Graves’ disease. This is an autoimmune disease that affects the thyroid gland.

SYMPTOMS

What are the symptoms of hyperthyroidism?

Hyperthyroidism often begins slowly. The symptoms can be mistaken for stress or other health problems. Common symptoms include:

• Unplanned weight loss
• Rapid heartbeat, abnormal heartbeat, or pounding of the heart
• Nervousness, anxiety, or touchiness
• Tremors (trembling of the hands and fingers)
• Changes in menstrual patterns such as lighter flow, less frequent periods
• Increased sensitivity to heat
• Increased sweating
• Bowel changes
• 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

Symptoms in older adults may be subtle. Examples are increased heart rate, fatigue during normal activities, and withdrawal. Healthcare providers may mistake hyperthyroidism for depression or dementia.

People who have Graves’ disease may have additional symptoms. One of the most common symptoms is swollen or bulging eyes. This can cause your eyes to be dry and red. You may also have:

• Tearing
• Blurry or double vision
• Sensitivity to light

CAUSES & RISK FACTORS

What causes hyperthyroidism?

Grave’s disease is by far the most common cause of hyperthyroidism in Canada. Normally, the immune system helps protect the body against viruses, bacteria and other foreign substances. An autoimmune disease causes it to attack your body’s tissues and/or organs. With Graves’ disease, the immune system stimulates 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:

• Hyperfunctioning (overactive)thyroid nodules. One or more nodules or lumps in the thyroid grow. This increases the production of the thyroid 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. Thyroiditis could lead to hypothyroidism (underactive thyroid) over time.

Consuming foods or medicines that contain high levels of iodine can also lead to hyperthyroidism. In rare cases, the cause could be a benign (noncancerous) tumor on the pituitary gland.

DIAGNOSIS & TESTS

How is hyperthyroidism diagnosed?

Contact your doctor if you have symptoms of an overactive thyroid. They may check for an enlarged thyroid gland, rapid pulse, moist skin, eye changes and a slight tremor in your fingers or hand. Your healthcare provider may also do a blood test to measure the amount of thyroid hormone in your blood. This confirms the diagnosis.

Your healthcare provider may do a thyroid scan to find the cause. If your entire thyroid is affected, you have Graves’ disease. Or the healthcare provider will look for thyroid nodules or an inflammation.

Your healthcare provider also may do a radioactive iodine uptake test. This test measures your thyroid’s ability to take up iodine. A high uptake of iodine means your thyroid gland may be producing too much hormone. This indicates Graves’ disease or a hyperfunctioning thyroid nodule. A low uptake of iodine indicates thyroiditis as the cause.

PREVENTION

Can hyperthyroidism be prevented or avoided?

You cannot prevent hyperthyroidism. However, some people are more at risk for the condition. This includes people who:

• Were born female
• Have a family history of thyroid disease
• Are younger than 40 or older than 60
• Have certain problems, such as type 1 diabetes, pernicious anemia, or an immune system disorder
• Consume large amounts of iodine, either through food or medicine

TREATMENT

How is hyperthyroidism treated?

There are several treatments for hyperthyroidism. The best one for you depends on your age, health, cause, and the severity of your condition. The goal is to control your thyroid levels and make them normal. Doing this relieves symptoms and prevents future health problems. Treatments include:

• Radioactive iodine. You take a pill or liquid by mouth. It gets into the blood stream and destroys overactive thyroid cells. This causes the level of thyroid hormone in the body to decrease. Symptoms often lessen in 3 to 6 months. The result is permanent low thyroid activity (hypothyroidism). This condition 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. This is a better option for people who are pregnant or breastfeeding. Talk to your healthcare provider about possible side effects.
• A thyroidectomy is when 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. These drugs to slow your heart rate and reduce tremors and anxiety. They can be used with other forms of treatment. You should be able to stop taking them once your thyroid levels return to normal.

Living with hyperthyroidism

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. You can get calcium in your food, or your healthcare provider may recommend a calcium supplement. 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.
• Too much thyroid hormone can make it hard for some women to get pregnant. An overactive thyroid also can be harmful to the mother and baby during pregnancy. Most doctors test women’s thyroid hormone levels at this stage.

People who have Graves’ disease may develop red, swollen skin on their shins and feet. Try using over-the-counter creams with hydrocortisone for relief. You also may have eye problems due to Graves’ ophthalmopathy. To relieve these symptoms:

• Apply cool compresses to your eyes
• Wear sunglasses
• Use lubricating eyedrops
• Elevate the head of your bed to reduce blood flow to your head

FOR MORE INFORMATION

Thyroid Foundation of Canada

http://www.thyroid.ca/