The thyroid 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.
Types of Thyroid Disorders
Thyroid disorders include:
- Disorders that cause hyperthyroidism
- Disorders that cause hypothyroidism
- Thyroid nodules
- Thyroid cancer
Some disorders cause the thyroid to make more thyroid hormones than the body needs. This is called hyperthyroidism, 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 .
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 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:
- Treatment of hyperthyroidism
- Radiation treatment of certain cancers
- Thyroid removal
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.
3) Thyroid Nodules
A thyroid nodule 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 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:
a) Postpartum thyroidits - 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:
An autoimmune disease, like type 1 diabetes
A personal history or family history of thyroid disorders
Having had postpartum thyroiditis after a previous pregnancy
b) Silent or painless thyroiditis - Symptoms are the same as in postpartum thyroiditis, but they are not related to having given birth.
c) Subacute thyroiditis - 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.
5) Thyroid Cancer
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. 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:
- Have a history of exposure of the thyroid to radiation (but not routine X-ray exposure, as in dental X-rays or mammograms)
- Have a family history of thyroid cancer
- Are older than 40 years of age
A goiter is an abnormally enlarged thyroid gland. Causes of goiter include:
- Iodine deficiency. Iodine is a mineral that your thyroid uses for making thyroid hormones. Not getting enough iodine in your food and water can cause your thyroid to get bigger. This cause of goiter is uncommon in the United States because iodine is added to table salt.
- Hashimoto's disease
- Graves' disease
- Thyroid nodules
- Thyroid cancer
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.
Diagnosis of Thyroid Disorders
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:
- Thyroid nodules that take up excess radioiodine are making too much of the thyroid hormones, causing hyperthyroidism. These nodules show up brightly on the scan and are called "hot" nodules.
- Thyroid nodules that take up the same amount of radioiodine as normal thyroid cells are making a normal amount of thyroid hormones. These are called "warm" nodules.
- Thyroid nodules that do not take up radioiodine are not making thyroid hormones. They appear as defects or holes in the scan and are called "cold" nodules.
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 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.
Treatment of Thyroid Disorders
Treatment of Hyperthyroidism
- Your doctor's choice of treatment will depend on the cause of your hyperthyroidism and how severe your symptoms are. Treatment options include:
- Antithyroid medicines block the thyroid's ability to make new thyroid hormones. These drugs do not cause permanent damage to the thyroid.
- Radioiodine damages or destroys the thyroid cells that make thyroid hormones. For this treatment, your doctor will give you a higher dose of a different type of radioiodine than is used for the radioiodine uptake test or the thyroid scan.
- Surgery to remove most of the thyroid.
- Beta-blockers are medicines that block the effects of thyroid hormones on the body. These medicines can be helpful in slowing your heart rate and reducing other symptoms until one of the other forms of treatment can take effect. Beta-blockers do not reduce the amount of thyroid hormones that are made.
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.
Treatment of Hypothyroidism
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. 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, 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 of Thyroid Nodules
Treatment depends on the type of nodule or nodules that you have. Treatments include:
- Watchful waiting. If your nodule is not cancerous, your doctor may decide to simply watch your condition. This involves giving you regular physical exams, blood tests, and perhaps thyroid ultrasound tests. If your nodule does not change, you may not need further treatment.
- Radioiodine. If you have nodules that are making too much of the thyroid hormones, radioiodine treatment may be used. The radioiodine is absorbed by the thyroid nodules, and it causes them to shrink and make smaller amounts of thyroid hormones.
- Alcohol ablation. In this procedure, your doctor injects alcohol into thyroid nodules that make too much of the thyroid hormones. The alcohol shrinks the nodules and they make smaller amounts of thyroid hormones.
- Surgery. All nodules that are cancerous are surgically removed. Sometimes, nodules that are not cancerous but are big enough to cause problems breathing or swallowing are also surgically removed.
Treatment of Thyroid Cancer
Surgery. The main treatment for thyroid cancer is to remove the entire thyroid gland, or as much of it as can be safely removed. Often, surgery alone will cure the thyroid cancer, especially if the cancer is small.
Radioiodine. A large dose of radioiodine will destroy thyroid cancer cells with little or no damage to other parts of the body.
Treatment of Goiter
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:
- Radioiodine to shrink the goiter, especially if parts of the goiter are overactive
- Surgery to remove part or almost all of the thyroid
Thyroid Disorders & Pregnancy
Both hyperthyroidism and hypothyroidism can make it more difficult for you to become pregnant.
Hyperthyroidism that is not properly treated during pregnancy can cause:
- Early labor and premature babies
- Preeclampsia, a serious condition starting after 20 weeks of pregnancy that causes high blood pressure and problems with the kidneys and other organs
- Fast heart rate of the developing baby
- Smaller babies
Women who have hypothyroidism that is not diagnosed or properly treated during pregnancy may be at increased risk for:
- Anemia (lower than normal number of healthy red blood cells)
- Low birth weight babies
- Problems with brain development in the baby
- Abnormal bleeding after giving birth
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:
- Prematurely gray hair
- White patches on the skin
- Type 1 diabetes
Exercise and Thyroid Disorders
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.
Getting Tests for Thyroid Disease
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:
- Pernicious anemia
- Type 1 diabetes
- Prematurely gray hair
At any age, be sure to ask your doctor about any thyroid disorder symptoms you might have.
Reference: U.S. Dept. of Health and Human Services