Hyperthyroidism

Hyperthyroidism, also called overactive thyroid, is a condition where your thyroid makes too much thyroid hormone. This speeds up your metabolism and affects other bodily functions, like digestion and heart rate. It can lead to symptoms like a rapid heartbeat, weight loss and feeling anxious or nervous.

Many conditions can cause hyperthyroidism, but the most common is Graves’ disease. Treatment for hyperthyroidism usually involves medication to stop your thyroid from making too much hormone. It can sometimes include surgery to remove some or all of your thyroid gland, depending on the cause. About 1 in 100 people over age 12 in the U.S. has an overactive thyroid.

Symptoms of hyperthyroidism

Hyperthyroidism symptoms can include:

• Fast or irregular heart rate
• Feeling anxious, nervous and/or irritable
• Shakiness, like hand tremors
• Increased sweating and warm, moist skin
• Unexpected weight loss
• Diarrhea or more frequent pooping
• Hair loss or brittle hair
• Difficulty sleeping
• Missed or irregular menstrual periods
• Swelling and enlargement of your neck
• Swelling or bulging of your eyes

Symptoms can start suddenly or develop slowly over time. You may have some of these and not others, or many of them at the same time. It’s important to see a healthcare provider if you develop any of these symptoms.

Hyperthyroidism causes

Medical conditions and situations that can cause hyperthyroidism include:

• Graves’ disease: This autoimmune condition is the most common cause of hyperthyroidism. Your chances of developing it increase if you have a biological family history of thyroid disease and/or another autoimmune condition.
• Thyroid nodules: These are lumps or growths of cells in your thyroid gland. They can sometimes produce excess thyroid hormone. They’re rarely cancerous.
• Thyroiditis: This is inflammation of your thyroid gland. It can cause hyperthyroidism temporarily.
• Too much iodine: Consuming too much iodine (through foods or medications) can cause your thyroid to produce more thyroid hormone. Iodine is a mineral that your thyroid uses to create thyroid hormone.
• TSH-releasing pituitary adenoma: This is a growth in your pituitary gland that releases excess thyroid-stimulating hormone (TSH). This is a very rare cause of hyperthyroidism.

Risk factors

Factors that increase your risk of developing hyperthyroidism include:

• Biological family history of thyroid disease and/or autoimmune conditions
• Using nicotine products, like cigarettes and tobacco
• Pregnancy within the last six months
• Eating foods with lots of iodine or taking medication containing iodine

How doctors diagnose overactive thyroid

Diagnosing hyperthyroidism may involve multiple steps, including:

• A physical exam: Your healthcare provider will do a physical exam to check for signs of hyperthyroidism, like an enlarged thyroid, a fast heart rate and warm, moist skin.
• Thyroid blood tests: Blood tests can check your thyroid hormone levels. When you have hyperthyroidism, levels of the thyroid hormones T3 and T4 are above normal. Thyroid-stimulating hormone (TSH) is often lower than normal.
• Thyroid antibody blood test: This test can check if Graves’ disease is the cause.
• Imaging tests: Various imaging tests of your thyroid can help diagnose hyperthyroidism and its cause. They include a radioactive iodine uptake (RAIU) test and a thyroid ultrasound.

How is hyperthyroidism treated?

There are many treatment options for hyperthyroidism. The goal of treatment is to bring your thyroid hormone levels to a normal level. Depending on the cause, some options may be better for you than others. Your healthcare provider will discuss each option with you. Together, you can decide on a treatment plan.

Antithyroid medications

Methimazole (Tapazole®) and propylthiouracil (PTU) stop your thyroid from making thyroid hormone. These medications are the most common treatment for hyperthyroidism. They can usually control thyroid function within two to three months. Your symptoms may get better within days to weeks.

Radioactive iodine (RAI) therapy

RAI therapy involves taking radioactive iodine by mouth in a single capsule or liquid dose. It targets thyroid cells and destroys them. But it can slow down your thyroid too much and lead to underactive thyroid (hypothyroidism). If this happens, you’ll need to take thyroid hormone medication to replace what your thyroid stops making.

Surgery

A surgeon may remove all or part of your thyroid gland. This will correct hyperthyroidism. But it can also lead to hypothyroidism. You’ll need lifelong treatment with thyroid hormones.

Beta-blockers

Beta-blockers are medications that can help manage symptoms such as a fast heartbeat, nervousness and shakiness. But they don’t change the level of hormone in your blood. Your provider may recommend beta-blockers along with another treatment.

Each of these treatments has specific side effects and risks. Your provider will go over them with you. Don’t hesitate to ask questions.

What happens if hyperthyroidism is left untreated?

Complications from untreated or undertreated hyperthyroidism include:

• Atrial fibrillation (AFib)
• Congestive heart failure
• Infertility
• Ischemic stroke
• Thyroid eye disease
• Osteoporosis

A rare and life-threatening complication of hyperthyroidism is thyroid storm. It happens when your thyroid makes and releases a large amount of thyroid hormone in a short amount of time. It’s an emergency that requires immediate medical attention.

What can I expect if I have this condition?

Hyperthyroidism is a treatable condition. Most people do well with treatment. While you might need to take medication for the rest of your life, this will help keep your thyroid hormone levels in a healthy range. Hyperthyroidism likely won’t affect your quality of life as long as you’re getting treatment.

Does hyperthyroidism cause weight gain?

Hyperthyroidism doesn’t typically cause weight gain. In fact, some people lose weight, even with an increased appetite. This is because hyperthyroidism speeds up your metabolic rate, causing your body to burn more calories. Hypothyroidism (underactive thyroid) slows down your metabolism, which may lead to weight gain.