What is hypothyroidism?

Hypothyroidism is the most common type of thyroid disorder. It means your thyroid gland is not active enough. This tiny gland is found in the front of your neck. Its job is to make thyroid hormone. If the gland is underactive, it may not make enough thyroid hormone.

Thyroid hormones control how your body uses energy to do its work. These hormones affect almost every organ in your body. When your thyroid doesn’t make enough of these hormones, parts of your body slow down.  

What causes hypothyroidism?

The most common cause of hypothyroidism is an autoimmune disorder. This means your immune system sees your normal tissues as strange and starts to attack itself. It makes antibodies against the thyroid gland. The normal thyroid cells are overrun by white blood cells and scar tissue. Another cause may be treatment for an overactive thyroid gland. That may include radioactive iodine therapy or surgery. Hypothyroidism may also develop shortly after pregnancy.

A condition called secondary hypothyroidism can also sometimes happen. It’s when your pituitary gland does not make enough thyroid stimulating hormone. The pituitary gland then no longer tells the thyroid gland to make enough thyroid hormones.

Newborns are tested at birth for hypothyroidism. This condition is called congenital hypothyroidism. It must be treated right away. It can affect a baby’s brain and nervous system.

Who is at risk for hypothyroidism?

You may be more likely to have hypothyroidism if you:

• Are a woman
• Are older than age 60
• Have had thyroid problems or thyroid surgery in the past
• Have a family history of thyroid problems
• Have certain conditions, such as type 1 diabetes or rheumatoid arthritis
• Have Turner syndrome, a genetic condition that affects women
• Are pregnant or have had a baby within the last 6 months
• Have an iodine deficiency. Your body needs iodine to make thyroid hormone.

What are the symptoms of hypothyroidism?

Symptoms are different for each person. They are often hard to notice and start slowly. They may be mistaken for symptoms of depression. Here are the most common symptoms and signs:

• Dull facial expressions
• Tiredness and lack of energy (fatigue)
• Not being able to handle cold
• Hoarse voice
• Slow speech
• Droopy eyelids
• Puffy and swollen face
• Weight gain
• Constipation
• Sparse, coarse, and dry hair
• Coarse, dry, and thickened skin
• Hand tingling or pain (carpal tunnel syndrome)
• Slow pulse
• Muscle cramps
• Joint pain
• Sides of eyebrows thin or fall out
• Confusion
• Increased or irregular menstrual flow in women

These symptoms may look like other health problems. Always see your healthcare provider for a diagnosis.

How is hypothyroidism diagnosed?

Your healthcare provider will ask about your past health. You will also need a physical exam. Blood tests can also help diagnose hypothyroidism. They can measure the amount of thyroid hormone and thyroid-stimulating hormones in your blood. Other blood tests can measure certain substances called antibodies that attack the thyroid gland.

How is hypothyroidism treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

The goal of treatment is to return your level of thyroid hormone back to normal. You may need to take medicine that gives you a dose of thyroid hormones. This dose may need to be changed over time. You will likely need to take this medicine for the rest of your life. You will need follow-up blood tests to make sure you are taking the correct dose of thyroid hormone replacement. Always check with your healthcare provider before switching brands of medicine.

What are possible complications of hypothyroidism?

If your hypothyroidism is not treated, these complications may happen:

• Anemia
• Low body temperature
• Heart failure
• High (elevated) cholesterol levels

When should I call my healthcare provider?

Tell your healthcare provider if your symptoms get worse or you have new symptoms. If you are a woman of childbearing age and want to become pregnant, talk with your healthcare provider first.

Key points about hypothyroidism

• Hypothyroidism means your thyroid gland is underactive. It isn’t making enough thyroid hormone. The most common cause is when your immune system starts to attack itself.
• Symptoms include dull facial expressions, tiredness, and weight gain.
• Blood tests help to diagnose this condition. They can measure the amount of thyroid hormone, thyroid-stimulating hormone, and antibodies that attack your thyroid.
• The goal of treatment is to return your levels of thyroid hormone back to normal.
• Untreated hypothyroidism may lead to anemia, low body temperature, and heart failure.
• Treatment may include medicine that replaces lost thyroid hormones. You may need to take thyroid hormones for the rest of your life.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your provider tells you.
• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new directions your provider gives you.
• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

What is hyperthyroidism?

Hyperthyroidism means your thyroid gland is too active. This tiny butterfly type of gland is found in your neck. An overactive thyroid gland makes too much thyroid hormone. This makes your metabolism work at a faster rate.

What causes hyperthyroidism?

Hyperthyroidism has several causes. These may include:

• Graves disease. It is the most common cause of hyperthyroidism. This is an autoimmune disorder. It happens when an antibody overstimulates the thyroid. This condition is most often found in young to middle-aged women. It also tends to run in families.
• Toxic nodular goiter. This condition happens when one or more lumps (nodules) of the thyroid gland make thyroid hormone independently from the normal feedback mechanism. Health experts don't know what causes this to happen. In most cases, the nodules are not cancer (benign). But in rare cases, the overactive thyroid tissue is cancer.
• Thyroiditis. This occurs when the thyroid becomes irritated. It temporarily causes the thyroid to release large amounts of thyroid hormone. The thyroid then often becomes underactive until it recovers. Viruses are often the cause of thyroiditis.

Hyperthyroidism may occur for other reasons. These include:

• Taking too much thyroid hormone medicine to treat an underactive thyroid
• Having too much iodine in your diet or in medicines (very rare)
• Having a noncancerous tumor in the pituitary gland that makes your thyroid overactive

Who is at risk for hyperthyroidism?

These things may make it more likely for you to have hyperthyroidism:

• You are a woman.
• You are older than age 40.
• You have had thyroid problems in the past.
• Your family has a history of thyroid problems.
• You have certain conditions, such as type 1 diabetes.
• You consume too much iodine. This can happen if you eat a lot of iodine-rich foods or take too much medicine that has this chemical.
• You are pregnant or have had a baby in the last 6 months.

What are the symptoms of hyperthyroidism?

Symptoms are different for each person. Here are the most common ones:

• Nervousness
• Irritability
• Sweating more than normal
• Thinning of the skin
• Fine, brittle hair
• Weak muscles, especially in the upper arms and thighs
• Shaky hands
• Fast heartbeat (palpitations)
• High blood pressure
• More bowel movements than normal, diarrhea
• Weight loss
• Trouble dealing with the heat
• Problems sleeping
• Prominent eyes
• Sensitivity to bright light
• Confusion
• Irregular menstrual cycle in women
• Tiredness and lack of energy (fatigue)
• Larger than normal thyroid gland (goiter)

• Pain in the lower neck in the thyroid gland (with thyroiditis)

These symptoms may look like other health problems. Always see your healthcare provider for a diagnosis.

How is hyperthyroidism diagnosed?

Your healthcare provider will ask about your health history. You will also need a physical exam. Other tests that can help diagnose hyperthyroidism include:

• Blood tests. They can measure the amount of thyroid hormone and thyroid stimulating hormone in your blood.
• Thyroid ultrasound. This test can see if your thyroid gland has any nodules. 
• Thyroid scan. This test uses a radioactive substance to make an image of the thyroid.

How is hyperthyroidism treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

Treatment may include:

• Medicine. It can help lower the level of thyroid hormones in the blood.
• Radioactive iodine. It comes in the form of a pill or liquid. It slowly destroys the cells of the thyroid gland so that less thyroid hormone is made.
• Surgery. You may need to have all or part of your thyroid removed.
• Beta blockers. These medicines block the action of the thyroid hormone on the body. That helps with rapid heart rate and palpitations.
• Steroids. These can be used to quiet the inflammation causing some forms of thyroiditis (in some cases)

What are possible complications of hyperthyroidism?

If your hyperthyroidism is not treated, these complications may happen:

• Thyroid crisis (when symptoms get worse because of stress or illness)
• Heart problems, such as an abnormal rhythm or heart failure
• Weak, brittle bones (osteoporosis)
• Pregnancy problems, such as miscarriage, early delivery, and preeclampsia or high blood pressure

When should I call my healthcare provider?

Tell your healthcare provider if your symptoms get worse or you have new symptoms. If you are a woman of childbearing age with one of these thyroid conditions and want to become pregnant, talk with your provider first.

Key points about hyperthyroidism

• Hyperthyroidism means you have too much thyroid hormone in your bloodstream. This tiny gland is found in your neck. If it is overactive, it makes too much thyroid hormone. Your body’s metabolism then begins to work at a faster rate.
• This condition can be caused by Graves disease, toxic nodular goiter, thyroiditis, and taking too much thyroid medicine.
• Symptoms may include nervousness, irritability, extra sweating (perspiration), and fine, brittle hair.
• Treatment may include medicine, radioactive iodine, surgery, or beta-blocking medicine.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your provider tells you.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new directions your provider gives you.
• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your healthcare provider if you have questions, especially after office hours and on weekends.

Thyroid Cancer: Introduction

What is cancer?

Cancer starts when cells in the body change (mutate) and grow out of control. To help you understand what happens when you have cancer, let's look at how your body works normally. Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body doesn't need them any longer.

Cancer is made up of abnormal cells that grow even though your body doesn't need them. In most cancers, the abnormal cells grow to form a lump or mass called a tumor. If cancer cells are in the body long enough, they can grow into (invade) nearby tissues. They can even spread to other parts of the body (metastasize).

What is the thyroid gland?

The thyroid gland is part of the endocrine system. It makes and helps control hormones and the metabolism in your body. It's in the front of your neck, over your windpipe (trachea). It's below your Adam’s apple (thyroid cartilage) and above your collarbone. You often can’t see or feel your thyroid.

It’s shaped like a butterfly with 2 lobes—a right and left lobe. The lobes are joined by a bridge of tissue called the isthmus.

The thyroid is made up of 2 main types of cells:

• Follicular cells. These use iodine to make thyroid hormones. These hormones help control your metabolism.
• C cells or parafollicular cells. These make the hormone calcitonin. This helps control calcium levels.

What is thyroid cancer?

Thyroid cancer starts in the cells that make up the thyroid gland.

There are 5 main types of thyroid cancer (or carcinoma):

• Papillary cancer. This is the most common type. It starts in the follicular cells. It tends to form in only 1 side of the thyroid gland and grow slowly. This type of thyroid cancer may spread to lymph nodes in the neck.

• Follicular cancer. This cancer also forms in the follicular cells of thyroid cancer. It's the next most common type and accounts for about 1 in 10 cases. It's more common in countries where people don't get enough iodine in their diet. This type of thyroid cancer may spread to other areas of the body. It doesn't spread to the lymph nodes very often.

• Hurthle cell cancer. This is a rare form of follicular thyroid cancer. It's harder to find and treat. It tends to not cause symptoms and has often spread to nearby lymph nodes by the time it's found.

• Medullary thyroid cancer (MTC). This is a rare type of thyroid cancer that starts in the C cells. It is also considered a neuroendocrine tumor. It produces a lot of calcitonin and tends to spread very fast. 

• Anaplastic cancer. This is also called undifferentiated thyroid cancer. It's very rare. It tends to grow and spread quickly. It's hard to treat.

Most thyroid changes are not cancer

Changes in the thyroid gland are often easy to see and feel. Lumps or bumps, called nodules, are common. Most of them are not cancer (95% to 96% are benign). And they may not need to be treated. Growths that are not cancer don’t spread from the thyroid to other parts of your body. 

Thyroid adenomas are small nodules that start in the thyroid gland. They're not cancer. Many times, they're only found while looking at the area around the thyroid for another reason.

Some thyroid adenomas make thyroid hormone. If an adenoma makes too much thyroid hormone, it can cause hyperthyroidism (toxic nodule). This is when there's too much thyroid hormone in your body. It can cause severe tiredness (fatigue), sweating, tremors, and heart palpitations. It may need to be treated.

Some signs that a nodule may be cancer and not an adenoma or other benign nodule include:

• The nodule is not making hormones.

• The nodule is solid instead of filled with fluid, like a cyst.

• The nodule is growing fast.

• Lymph nodes around the thyroid gland are swollen. 

How thyroid cancer spreads

When thyroid cancer spreads outside the thyroid gland, it most often goes to nearby lymph nodes first. It can also spread to nearby blood vessels and other tissues in the neck. Over time, it can spread to distant parts of the body, such as the lungs and bones.

Talk with your healthcare provider

If you have questions about thyroid cancer, talk with your healthcare provider. Your healthcare provider can help you understand more about this cancer.