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 body’s metabolism. It affects your heart rate and the function of your other organs. It also affects your muscles, bones, and menstrual cycles (for women).
Hyperthyroidism can be related to Graves’ disease. This is an autoimmune disease that affects the thyroid gland.
Symptoms of hyperthyroidism
Hyperthyroidism often begins slowly. Its 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 or less frequent periods, in women
- Increased sensitivity to heat
- Increased sweating
- Bowel changes
- An enlarged thyroid gland (called a goiter), which can appear as swelling at the base of the neck
- Muscle weakness
- Trouble sleeping
- Increased appetite
Symptoms in older adults may be subtle. Examples are increased heart rate, fatigue during normal activities, and withdrawal. Doctors 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:
- Blurry or double vision
- Sensitivity to light
What causes hyperthyroidism?
In more than 70% of cases, hyperthyroidism is caused by Graves’ disease. Normally, the immune system helps protect your body against viruses, bacteria, and other substances. An autoimmune disease causes it to attack your body’s tissues and/or organs. With Graves’ disease, the immune system stimulates your thyroid, making it produce too much hormone. Doctors think Graves’ disease may run in families. It is most common among young women.
Two other common causes for hyperthyroidism are:
- 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. This causes extra thyroid hormone to leak into your 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.
How is hyperthyroidism diagnosed?
Contact your doctor if you have symptoms of an overactive thyroid. He or she will check for an enlarged thyroid gland, rapid pulse, moist skin, eye changes, and a slight tremor in your fingers or hand. Your doctor also will do a blood test to measure the amount of thyroid hormone in your blood. This confirms the diagnosis.
Your doctor may do a thyroid scan to find the cause. If your entire thyroid is affected, you have Graves’ disease. Or the doctor will look for thyroid nodules or an inflammation.
Your doctor 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.
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
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 your blood stream and destroys the overactive thyroid cells. This causes the level of thyroid hormone in your 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, the treatment has been used for more than 60 years without any problems. Most adults in the United States who have hyperthyroidism are treated with radioactive iodine. This option is not suitable for women who are pregnant or breastfeeding.
- Anti-thyroid medicine. These drugs tell your thyroid to produce fewer hormones. Symptoms begin to improve in 6 to 12 weeks as your hormone levels adjust. Treatment can last for at least a year. This is a better option for women who are pregnant or breastfeeding. Talk to your doctor about possible side effects.
- Surgery. A thyroidectomy is when the doctor removes most of your thyroid gland. After surgery, you likely will develop hypothyroidism. You can take thyroid supplements to restore your hormone levels to normal.
- Beta blockers. These drugs 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. These 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 prevent your body from absorbing calcium into your bones. You can get calcium in your food, or your doctor may recommend a calcium supplement.
- Thyrotoxic crisis. A sudden worsening of hyperthyroidism symptoms that leads to a fever, rapid pulse, and delirium. Signs of delirium include decreased awareness, confusion, and restlessness. See a doctor right away if this occurs.
- Infertility. 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 a cool compress to your eyes.
- Wear sunglasses.
- Use lubricating eye drops.
- Elevate the head of your bed to reduce blood flow to your head.
Questions to ask your doctor
- What is the cause of my hyperthyroidism?
- Do I have Graves’ disease?
- What types of food and medicine contain high levels of iodine?
- What is the best treatment?
- Will I need to take medicine? If so, for how long and what are the side effects?
- Will I need surgery? If so, what are the benefits and risks?
- Are there any lifestyle changes I can make to relieve my symptoms?
- Am I at risk for related health problems?
Copyright © American Academy of Family Physicians
This information provides a general overview and may not apply to everyone. Talk to your family doctor to find out if this information applies to you and to get more information on this subject.