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Your thyroid (THY-roid) is a small gland found at the base of your neck, just below your Adam's apple. The thyroid produces two main hormones called T3 and T4. These hormones travel in your blood to all parts of your body. The thyroid hormones control the rate of many activities in your body. These include how fast you burn calories and how fast your heart beats. All of these activities together are known as your body's metabolism. A thyroid that is working right will produce the right amounts of hormones needed to keep your body’s metabolism working at a rate that is not too fast or too slow.
Women are more likely than men to develop thyroid disorders. Thyroid disorders that can affect women include:
Some disorders cause the thyroid to make more thyroid hormones than the body needs. This is called hyperthyroidism (hy-pur-THY-roi-diz-uhm), or overactive thyroid. The most common cause of hyperthyroidism is Graves' disease. Graves’ disease is an autoimmune disorder, in which the body's own defense system, called the immune system, stimulates the thyroid. This causes it to make too much of the thyroid hormones. Hyperthyroidism can also be caused by thyroid nodules that prompt excess thyroid hormones to be made (see What are thyroid nodules?).
At first, you might not notice symptoms of hyperthyroidism. They usually begin slowly. But over time, a speeded up metabolism can cause symptoms such as:
In addition to these symptoms, people with hyperthyroidism may have osteoporosis, or weak, brittle bones. In fact, hyperthyroidism might affect your bones before you have any of the other symptoms of the disorder. This is especially true of postmenopausal women, who are already at high risk of osteoporosis.
Hypothyroidism (hy-poh-THY-roi-diz-uhm) is when your thyroid does not make enough thyroid hormones. It is also called underactive thyroid. The most common cause of hypothyroidism in the United States is Hashimoto's disease. Hashimoto’s disease is an autoimmune disease, in which the immune system mistakenly attacks the thyroid. This attack damages the thyroid so that it does not make enough hormones. Hypothyroidism also can be caused by:
In rare cases, problems with the pituitary gland can cause the thyroid to be less active.
In addition to these symptoms, people with hypothyroidism may have high blood levels of LDL cholesterol. This is the so‑called "bad" cholesterol, which can increase your risk for heart disease.
A thyroid nodule (NAHD-yool) is a swelling in one section of the thyroid gland. The nodule can be solid or filled with fluid or blood. You can have just one thyroid nodule or many.
Most thyroid nodules do not cause symptoms. But some thyroid nodules make too much of the thyroid hormones, causing hyperthyroidism. Sometimes, nodules get to be big enough to cause problems with swallowing or breathing. In fewer than 10 percent of cases, thyroid nodules are cancerous.
Thyroid nodules are quite common. By the time you reach the age of 50, you have a 50 percent chance of having a thyroid nodule larger than a half inch wide. We do not know why nodules form in otherwise normal thyroids.
You can sometimes see or feel a thyroid nodule yourself. Try standing in front of a mirror and raise your chin slightly. Look for a bump on either side of your windpipe below your Adam's apple. If the bump moves up and down when you swallow, it may be a thyroid nodule. Ask your doctor to look at it.
Thyroiditis (thy-roi-DY-tiss) is inflammation, or swelling, of the thyroid. There are several types of thyroiditis, one of which is Hashimoto's thyroiditis. Other types of thyroiditis include:
Like Hashimoto's disease, postpartum thyroiditis seems to be caused by a problem with the immune system. In the United States, postpartum thyroiditis occurs in about 5 to 10 percent of women. The first phase starts 1 to 4 months after giving birth. In this phase, you may get symptoms of hyperthyroidism because the damaged thyroid is leaking thyroid hormones out into the bloodstream. The second phase starts about 4 to 8 months after delivery. In this phase, you may get symptoms of hypothyroidism because, by this time, the thyroid has lost most of its hormones. Not everyone with postpartum thyroiditis goes through both phases. In most women who have postpartum thyroiditis, thyroid function returns to normal within 12 to 18 months after symptoms start.
Risk factors for postpartum thyroiditis include having:
Silent or painless thyroiditis
Symptoms are the same as in postpartum thyroiditis, but they are not related to having given birth.
Symptoms are the same as in postpartum and silent thyroiditis, but the inflammation in the thyroid leads to pain in the neck, jaw, or ear. Unlike the other types of thyroiditis, subacute thyroiditis may be caused by an infection.
Most people with thyroid cancer have a thyroid nodule that is not causing any symptoms. If you have a thyroid nodule, there is a small chance it may be thyroid cancer. To tell if the nodule is cancerous, your doctor will have to do certain tests (see How are thyroid diseases diagnosed?). A few people with thyroid cancer may have symptoms. If the cancer is big enough, it may cause swelling you can see in the neck. It may also cause pain or problems swallowing. Some people get a hoarse voice.
Thyroid cancer is rare compared with other types of cancer. It is more common in people who:
A goiter is an abnormally enlarged thyroid gland. Causes of goiter include:
Usually, the only symptom of a goiter is a swelling in your neck. But a very large or advanced goiter can cause a tight feeling in your throat, coughing, or problems swallowing or breathing.
Having a goiter does not always mean that your thyroid is not making the right amount of hormones. Depending on the cause of your goiter, your thyroid could be making too much, not enough, or the right amount of hormones.
Thyroid disorders can be hard to diagnose because their symptoms can be linked to many other health problems. Your doctor will start by taking a medical history and asking if any of your family members has a history of thyroid disorders. Your doctor will also give you a physical exam and check your neck for thyroid nodules. Depending on your symptoms, your doctor may also do other tests, such as:
Testing the level of thyroid stimulating hormone (TSH) in your blood can help your doctor figure out if your thyroid is overactive or underactive. TSH tells your thyroid to make thyroid hormones. Depending on the results, your doctor might order another blood test to check levels of one or both thyroid hormones in your blood. If your doctor suspects an immune system problem, your blood may also be tested for signs of this.
Radioactive iodine uptake test
For this test, you swallow a liquid or capsule containing a small dose of radioactive iodine (radioiodine). The radioiodine collects in your thyroid because your thyroid uses iodine to make thyroid hormones. Then, a probe placed over your thyroid measures the amount of radioiodine in your thyroid. A high uptake of radioiodine means that your thyroid is making too much of the thyroid hormones. A low uptake of radioiodine means that your thyroid is not making enough of the thyroid hormones.
A thyroid scan usually uses the same radioiodine dose that was given by mouth for your uptake test. You lie on a table while a special camera creates an image of your thyroid on a computer screen. This test may be helpful in showing whether a thyroid nodule is cancerous. Three types of nodules show up in this test:
Hot nodules are almost never cancerous. A small percentage of warm and cold nodules are cancerous.
Thyroid fine needle biopsy
This test is used to see if thyroid nodules have normal cells in them. Local anesthetic may be used to numb an area on your neck. Then, a very thin needle is inserted into the thyroid to withdraw some cells and fluid. The withdrawal of cells and fluid is called a biopsy (BY-op-see). A special type of doctor called a pathologist (path-ol-uh-jist) examines the cells under a microscope to see if they are abnormal. Abnormal cells could mean thyroid cancer.
The thyroid ultrasound uses sound waves to create a computer image of the thyroid. This test can help your doctor tell what type of nodule you have and how large it is. Ultrasound may also be helpful in detecting thyroid cancer, although by itself it cannot be used to diagnose thyroid cancer. You may have repeat thyroid ultrasounds to see if your nodule is growing or shrinking.
Your doctor's choice of treatment will depend on the cause of your hyperthyroidism and how severe your symptoms are. Treatments include:
If your thyroid is destroyed by radioiodine or removed through surgery, you must take thyroid hormone pills for the rest of your life. These pills give your body the thyroid hormones that your thyroid would normally make.
Hypothyroidism is treated with medicine to supply the body with the thyroid hormones it needs to function right. The most commonly used medicine is levothyroxine (le-voh-thy-ROK-suhn). This is a man-made form of T4. It is exactly the same as the T4 that your thyroid makes. When you take T4, your body makes the T3 it needs from the T4 in the pills. A man-made form of T3, called liothyronine (ly-oh-THY-roh-neen), is also available. Some doctors and patients prefer a combination of T4 and T3 or T3 by itself. Most patients with hypothyroidism will need to be on thyroid hormone treatment for the rest of their lives.
Treatment depends on the type of nodule or nodules that you have. Treatments include:
The treatment for goiter depends on the cause of the goiter. If your goiter is caused by not getting enough iodine, you may be given an iodine supplement to swallow and T4 hormone, if need be. Other treatments include:
To date, we don’t know enough about alternative treatments for thyroid problems. Your doctor can explain which treatment options are best for you.
Both hyperthyroidism and hypothyroidism can make it more difficult for you to become pregnant.
Hyperthyroidism that is not properly treated during pregnancy can cause:
Women who have hypothyroidism that is not diagnosed or properly treated during pregnancy may be at increased risk for:
If you are pregnant or are thinking about becoming pregnant, ask your doctor if you need a thyroid test. This is especially true if you or a family member has a history of thyroid problems or conditions related to thyroid disorders, including:
Some people with thyroid problems may find exercise difficult. It is important to talk to your doctor about the right amount of physical activity for you.
Ask your doctor or nurse if you need to have a thyroid test. This is especially important if you are of childbearing age, have already had a thyroid problem, or have had surgery or radiotherapy affecting the thyroid gland. You may also be at higher risk if you have:
At any age, be sure to ask your doctor about any thyroid disorder symptoms you might have.
For more information about thyroid disease, call womenshealth.gov at 800-994-9662 (TDD: 888-220-5446) or contact the following organizations:
Thyroid disease fact sheet was reviewed by:
Jacqueline Jonklass, M.D., Ph.D., M.P.H.
Division of Endocrinology and Metabolism
Department of Medicine
Mark Helfand, M.D., M.S., M.P.H.
Director, Oregon Evidence-Based Practice Center
Assistant Professor, School of Medicine
Oregon Health and Science University
Content last updated: July 16, 2012.