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Illustration by Wenzdai Figueroa

Hypothyroidism occurs when your body doesn’t produce enough thyroid hormones. The thyroid is a small, butterfly-shaped gland that sits in front of your windpipe. It releases hormones that help your body regulate and use energy.

Thyroid hormones help control functions including how your heart beats and how your digestive system works. Without the right amount of thyroid hormones, your body’s natural functions begin to slow down.

Also called underactive thyroid, hypothyroidism usually affects people over the age of 60 and is more common in women than men. It may be discovered through a routine blood test or after symptoms begin.

Subclinical hypothyroidism is the name given to an early, mild form of the condition.

If you’ve recently received a hypothyroidism diagnosis, it’s important to know that treatment is considered simple, safe, and effective.

Most treatments rely on supplementing your low hormone levels with artificial hormones. These hormones will replace what your body isn’t producing on its own and help return your body’s functions to normal.

Hypothyroidism vs. hyperthyroidism

Hypothyroidism and hyperthyroidism have opposite effects. With hyperthyroidism, or overactive thyroid, the thyroid gland makes too much thyroid hormone.

The greater amount of thyroid hormone causes some functions in your body to become faster, like your heart rate. You may also experience weight loss and difficulty sleeping.

Hyperthyroidism is less common than hypothyroidism. It affects around 1 percent of people ages 12 and older in the United States. Like hypothyroidism, it occurs more frequently in women and people over age 60.

Medications, radioiodine therapy, and surgery may be used to treat hyperthyroidism.

Hypothyroidism is a fairly common condition. In the United States, almost 5 percent of people ages 12 years old and up have hypothyroidism.

The disease gets more common with age. People over 60 years old experience it more frequently.

Women are more likely to have an underactive thyroid. In fact, 1 in 8 women will develop thyroid issues.

The effects of hypothyroidism on the body often vary among different people and may be difficult to identify. The severity of the condition also affects which signs and symptoms appear and when.

Early symptoms can include weight gain and fatigue. Note that these both become more common as you age, regardless of your thyroid’s health.

As a result, you may not realize that these changes are related to your thyroid until more symptoms appear. For instance, these may include skin changes associated with hypothyroidism, like scaly, rough, and dry skin and fragile nails.

In general, the most common signs and symptoms of hypothyroidism include:

For most people, symptoms of the condition progress gradually over many years. As the thyroid slows more and more, the symptoms may become more easily identified. Of course, many of these symptoms also become more common with age in general.

If you suspect your symptoms are the result of a thyroid problem, talk with your doctor. They can order a blood test to determine whether you have hypothyroidism.

If you don’t already have a primary care doctor, you can browse doctors in your area through the Healthline FindCare tool.

Hypothyroidism symptoms in adults

Besides the most common hypothyroidism symptoms, research indicates that hypothyroidism symptoms in men may also include erectile dysfunction.

Hypothyroidism symptoms in women may additionally include:

It’s also possible to develop hypothyroidism during pregnancy. Symptoms will usually be similar to those of other cases of hypothyroidism.

Hypothyroidism in young people

While hypothyroidism is less common in younger people, it can still occur. The condition may cause slower development in children and early puberty in teenagers.

Babies may also be born lacking thyroid function, a condition called congenital hypothyroidism. Symptoms of hypothyroidism in infants may include:

  • sleeping more than usual
  • constipation
  • difficulty with feeding
  • delayed growth (if the condition is untreated)

In some cases, babies with hypothyroidism may show no symptoms.

Severe hypothyroidism symptoms

If hypothyroidism isn’t treated, you may develop additional symptoms:

In rare cases, severe hypothyroidism may result in myxedema coma, a life threatening condition that requires emergency care. While the condition does not actually involve being in a coma, you may experience:

The most common causes of hypothyroidism are:

Less common causes include:

Hashimoto’s thyroiditis

Your immune system is designed to protect your body’s cells against invading bacteria and viruses. When unknown bacteria or viruses enter your body, your immune system responds by sending fighter cells to destroy the foreign cells.

Sometimes, your body confuses normal, healthy cells for invading cells. This is called an autoimmune response. If the autoimmune response isn’t regulated or treated, your immune system can attack healthy tissues. This can cause serious medical issues, including conditions such as hypothyroidism.

Hashimoto’s thyroiditis is an autoimmune condition and the most common cause of an underactive thyroid in the United States. This disease attacks your thyroid gland, causing damage that reduces thyroid function.

It most often affects middle-aged women, but it can occur in men and children. This condition also runs in families. If a family member has received a diagnosis of this disease, then your risk of having it is higher.

Radioactive iodine treatment for hyperthyroidism

If your thyroid gland produces too much thyroid hormone, you have a condition known as hyperthyroidism. Treatment for this condition aims to reduce and regulate thyroid hormone production.

Standard treatment for hyperthyroidism uses radioactive iodine to destroy thyroid cells. This may cause the levels of your thyroid hormone to remain low permanently.

Surgical removal of your thyroid

If your entire thyroid gland is removed as a result of thyroid problems, you’ll develop hypothyroidism. Using thyroid medication long term is the primary treatment.

If only a portion of the gland is removed, your thyroid may still be able to produce enough hormones on its own. Blood tests will help determine how much thyroid medication you may need.

Radiation therapy

If you’ve received a diagnosis of cancer of the head or neck, lymphoma, or leukemia, you may have undergone radiation therapy. Radiation used for the treatment of these conditions may slow or halt the production of thyroid hormone, leading to hypothyroidism.

Medications

Several medications may lower thyroid hormone production, resulting in hypothyroidism. These include ones used to treat mental health conditions, cancer, or heart disease, such as:

  • lithium, which treats mania in bipolar disorder
  • interleukin-2 (IL-2), an immunotherapy drug
  • anti-CTLA-4 medications, which treat melanoma
  • amiodarone (Pacerone), an antiarrhythmic drug
  • stavudine, a medication for HIV

Iodine deficiency

Iodine deficiency occurs infrequently in the United States, but it is the most common cause of hypothyroidism in other parts of the world. Iodine, which is needed to produce thyroid hormone, is found in foods including:

  • iodized salt
  • dairy
  • seafood
  • eggs

If you have iodine deficiency, you may develop swelling at the base of your neck. This is called a goiter. It’s caused by an enlarged thyroid gland.

Pituitary disorders

Hypothyroidism may also result from problems involving the pituitary gland. This small gland in the brain produces hormones that affect many bodily functions, including the thyroid gland.

Problems with the pituitary gland may cause thyroid issues. Pituitary disorders may result from:

This type of hypothyroidism is called secondary hypothyroidism because the thyroid gland functions normally. It’s less common than primary hypothyroidism, which is caused by a problem with the thyroid gland.

Congenital disease

Congenital hypothyroidism is hypothyroidism that’s present in children from birth. It affects between 1 in 2,000 and 1 in 4,000 newborns and is twice as common in females.

The condition occurs when the thyroid gland develops abnormally or is not present at all. Genetics or iodine deficiency may cause this. While some babies may show no symptoms, others will be less active or have trouble feeding.

U.S. hospitals test newborns for the condition. It’s important to treat congenital hypothyroidism to prevent it from delaying growth or mental development.

Pregnancy

Around 5 to 10 percent of pregnant people will develop postpartum thyroiditis several months after their pregnancy. While only some will need treatment, others will develop permanent hypothyroidism.

The following can increase the risk of postpartum thyroiditis:

  • history of postpartum thyroiditis
  • presence of antibodies to thyroid peroxidase in the blood
  • type 1 diabetes

De Quervain thyroiditis

An upper respiratory infection that damages thyroid cells may cause De Quervain thyroiditis, an uncommon condition that is also called subacute granulomatous thyroiditis. It’s most common in women and often occurs during the summer and fall.

Symptoms of de Quervain thyroiditis include:

  • pain in the neck, jaw, and throat
  • enlarged, tender thyroid gland
  • fever
  • fatigue
  • body pain

The condition may cause hyperthyroidism followed by hypothyroidism and last 2 to 8 weeks. Typically, thyroid function will then return to normal, though in some cases hypothyroidism may be permanent.

Factors that can increase your risk of developing hypothyroidism include:

  • being female
  • being at least 60 years old
  • being treated with radiation therapy to your neck or chest
  • recently being pregnant
  • having a family history of thyroid disorders
  • having certain autoimmune conditions, such as Sjögren’s disease and type 1 diabetes

Two primary tools are used to determine whether you have hypothyroidism: a medical evaluation and blood tests.

Medical evaluation

Your doctor will complete a thorough physical exam and medical history. They’ll check for physical signs of hypothyroidism, including:

In addition, your doctor will ask you to report any symptoms you’ve been experiencing, such as fatigue, constipation, or constantly feeling cold.

If you have a known family history of thyroid conditions, tell your doctor during this exam.

Blood tests

Blood tests are the only way to reliably confirm a diagnosis of hypothyroidism.

A thyroid-stimulating hormone (TSH) test measures how much TSH your pituitary gland is creating:

  • If your thyroid isn’t producing enough hormones, the pituitary gland will boost TSH to increase thyroid hormone production. The high TSH levels indicate hypothyroidism.
  • If you have hyperthyroidism, your TSH levels will be low, as your body is trying to stop excessive thyroid hormone production.

A thyroxine (T4) level test is also useful in diagnosing hypothyroidism. T4 is one of the hormones directly produced by your thyroid. Used together, T4 and TSH tests can help evaluate thyroid function.

Typically, if you have a low level of T4 along with a high level of TSH, you have hypothyroidism. If you have subclinical hypothyroidism, though, you may have normal T4 with a high TSH level.

Since there’s a spectrum of thyroid disease, other thyroid function tests may be necessary to properly diagnose your condition.

If your T4 test is normal, you may also receive a triiodothyronine (T3) test. Low T3 levels may indicate hypothyroidism, though again, T3 levels may be normal in subclinical hypothyroidism.

Finally, thyroid antibody tests look for antibodies in your blood to diagnose autoimmune thyroid disorders like Hashimoto’s thyroiditis.

Hypothyroidism is a lifelong condition. For many people, medication reduces or alleviates symptoms.

Hypothyroidism is best treated by using levothyroxine (Levoxyl, Synthroid). This synthetic version of the T4 hormone copies the action of the thyroid hormone your body would normally produce.

The medication is designed to return adequate levels of thyroid hormone to your blood. Once hormone levels are restored, symptoms of the condition are likely to disappear or at least become much more manageable.

Once you start treatment, it will take several weeks before you’ll begin feeling relief. You’ll require follow-up blood tests to monitor your progress. You and your doctor will work together to find a dose and a treatment plan that best addresses your symptoms. This can take some time.

In most cases, people with hypothyroidism must remain on this medication their entire lives. However, the amount you take may need to be adjusted, especially if you have Hashimoto’s thyroiditis. To make sure your medication is still working properly, your doctor will likely test your TSH levels yearly.

If blood levels indicate the medication isn’t working as well as it should, your doctor will adjust the dose until a balance is achieved.

Besides standard thyroid medications, animal extracts that contain thyroid hormone are also available. These extracts come from the thyroid glands of pigs. They contain both T4 and triiodothyronine (T3).

If you take levothyroxine, you’re only receiving T4. However, that’s all you need because your body is capable of producing T3 from the synthetic T4.

Research has found medications with animal extracts to be similar to levothyroxine. Other studies have indicated that taking animal thyroid extract may reduce thyroid symptoms but cause more side effects. Currently, animal thyroid extracts aren’t routinely recommended.

You can also buy glandular extract supplements in some health food stores. Additionally, studies suggest that selenium supplements may help people with hypothyroidism caused by autoimmune disease, though research is mixed.

Note that dietary supplements aren’t regulated as drugs by the Food and Drug Administration (FDA). Because of this, their potency, legitimacy, and purity aren’t guaranteed.

Use these products at your own risk. It’s important to tell your doctor if you decide to try a supplement so they can adjust your treatment accordingly.

Complications of hypothyroidism include:

As a general rule, you don’t need to follow a specific diet for hypothyroidism. However, there are some recommendations to keep in mind.

Eat a balanced diet

Your thyroid needs adequate amounts of iodine to fully function, but you don’t need to take an iodine supplement to achieve that.

There are plenty of iodine-rich foods, including:

  • iodized salt
  • dairy products like milk, yogurt, and cheese
  • eggs
  • seafood
  • seaweed

In general, a balanced diet should provide enough iodine for most people.

Monitor your soy intake

Soy may be linked to hypothyroidism. Drinking or eating too many soy products may lower thyroid function, especially in people with thyroid disorders. However, more research in this area is needed.

Soy is found in:

  • tofu
  • vegan cheese and meat products
  • soy milk
  • soybeans
  • soy sauce

It’s especially important for caregivers to monitor the soy intake of infants who need hypothyroidism treatment and also drink soy formula.

Be smart with fiber

Fiber may interfere with thyroid hormone absorption. Too much dietary fiber may prevent your body from getting the hormones it needs from thyroid medications.

Fiber is vital, so don’t skip it entirely. Instead, avoid taking your medication within several hours of eating high fiber foods.

Avoid taking thyroid medication with other supplements

If you take supplements or medications in addition to thyroid medications, try to take them at different times. Other medications can interfere with absorption, so it’s best to take your thyroid medication without other supplements, medications, or foods.

Even if you’re undergoing treatment, you may deal with long lasting issues or complications from hypothyroidism. However, there are ways to lessen the condition’s effect on your quality of life.

Monitor for other health conditions

There’s a link between other autoimmune diseases and hypothyroidism. Hypothyroidism often goes along with conditions such as:

Develop fatigue coping strategies

Despite taking medication, you may still experience fatigue from time to time. To help you manage low energy levels, it’s important that you:

A 2018 study found that yoga improved fatigue and other symptoms in a small group of people with hypothyroidism, though more research is needed.

Talk it out

Having a chronic health condition can be difficult, especially if it’s accompanied by other health concerns. Since hypothyroidism can cause depression and fatigue, it may also make your relationships more challenging.

Find people with whom you can openly express your feelings and experiences. This might be a:

  • mental health counselor
  • close friend
  • family member
  • support group of other people living with the condition

Some hospitals sponsor meetings for people with health conditions including hypothyroidism. Ask for a recommendation from your doctor and consider attending a meeting.

Research indicates that online communities may also help strengthen social connections, provide a supportive space, and help people with chronic illnesses share advice.

Support groups can help you connect with people who understand exactly what you’re experiencing while offering a guiding hand.

When levels of thyroid hormones are low, your body’s natural functions lag. This can cause a variety of symptoms, including fatigue, weight gain, and even depression.

A small 2016 study found that 60 percent of participants with hypothyroidism exhibited some symptoms of depression.

Hypothyroidism may cause a range of mental health difficulties. This can make diagnosing hypothyroidism difficult. Before making a treatment plan for mental health issues, doctors may consider testing for an underactive thyroid.

Depression and hypothyroidism can share several symptoms. These include:

The two conditions also have symptoms that may distinguish them from one another. For hypothyroidism, problems such as dry skin, constipation, and hair loss are common. For depression alone, these conditions wouldn’t be expected.

Depression is often a diagnosis made based on symptoms and medical history. Low thyroid function is diagnosed with a physical exam and blood tests. To see whether there’s a link between your depression and your thyroid function, your doctor can order these tests for a definitive diagnosis.

If your depression is caused only by hypothyroidism, correcting the thyroid disorder should treat the depression. If it doesn’t, your doctor may prescribe medications for both conditions. They’ll slowly adjust your doses until your depression and hypothyroidism are better managed.

While hypothyroidism has long been associated with depression, a 2016 study suggested it may be associated with anxiety too.

Researchers evaluated 100 people between the ages of 18 and 45 who had a known history of hypothyroidism. Using an anxiety questionnaire, they found that around 63 percent of them met the criteria for some form of anxiety.

Larger and more focused studies on anxiety may help determine whether a true connection exists between hypothyroidism and anxiety.

It’s important for you and your doctor to discuss all your symptoms when being evaluated for thyroid or mental health conditions.

People with thyroid problems can and very often do have healthy pregnancies. Still, hypothyroidism can pose a particular set of challenges for pregnancy.

Low thyroid function or unmanaged hypothyroidism during pregnancy can cause:

If you have hypothyroidism and are pregnant, it’s important to take the following steps during the time you’re expecting:

Talk with your doctor about testing

You can develop hypothyroidism while pregnant. Some doctors routinely check thyroid levels during pregnancy to monitor for low thyroid hormone levels. If your levels are lower than they should be, your doctor may suggest treatment.

Some people who never had thyroid problems before they were pregnant may develop them after having a baby. This is called postpartum thyroiditis.

In many cases, the condition resolves within 12 to 18 months, and medication is no longer required. However, around 20 percent of people with postpartum thyroiditis will need long-term therapy.

Stay up to date with your medication

Continue to take your medication as prescribed. It’s common to have regular testing so your doctor can make any necessary adjustments to your thyroid medication as your pregnancy progresses. This ensures that the baby is getting enough thyroid hormone for their brain and nervous system to develop normally.

Eat well

Your body needs more nutrients, vitamins, and minerals while you’re pregnant. Eating a balanced diet and taking multivitamins while pregnant can help you maintain a healthy pregnancy.

It’s also important to get enough iodine, which is essential for producing thyroid hormone. Aim to consume around 250 micrograms of iodine each day through food or supplements. Remember to talk with your doctor before starting any new supplements.

Your thyroid is responsible for many of your body’s daily functions, including metabolism, organ function, and temperature control. When your body doesn’t produce enough thyroid hormone, all of these functions can slow down.

If your thyroid gland doesn’t function properly, your basal metabolic rate — a measurement of the amount of energy your body uses at rest — may be low. As a result, an underactive thyroid may lead to some weight gain. The more severe the condition is, the greater your weight gain is likely to be.

The typical amount of weight gain isn’t very high, though. Most people will gain somewhere between 5 and 10 pounds.

Properly treating the condition may lead you to lose any weight you gained while your thyroid levels were not treated. However, keep in mind that that’s not always the case. Symptoms of an underactive thyroid, including weight gain, often develop over a long period of time and may not be caused by a thyroid disorder alone.

If your weight stays the same, it doesn’t mean the condition isn’t being properly treated. Instead, it may indicate that your weight gain was the result of lifestyle or other conditions rather than low hormone levels.

Once you’re treated for hypothyroidism, you may lose any weight you gained from low hormone levels. That’s because once your thyroid levels are restored, your ability to manage your weight returns to normal.

If you’re treating hypothyroidism but don’t see a change in your weight, you may still be able to lose weight if that’s a goal for you. Work with a doctor, registered dietitian, or personal trainer to develop a healthy eating plan and exercise strategy to reach or maintain a moderate weight.

Your body naturally goes through changes as you get older. If you notice a significant difference in how you feel or how your body is responding, talk with your doctor to see whether a thyroid problem may be affecting you. If you’re a woman over age 60, remember that you’re at higher risk of a thyroid disorder.

If you have hypothyroidism, you’ll probably need to take thyroid medications for the rest of your life. Still, it’s likely that medication will help relieve or resolve your symptoms. You may also benefit from joining a support group for people living with hypothyroidism.