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Hypothyroidism: Signs, Symptoms, and Treatment


September 10, 2021

Hypothyroidism occurs when the thyroid gland isn’t working properly. Around 5% of people in the U.S. have hypothyroidism. Many people who have hypothyroidism don’t know it, because they have no signs of disease or their symptoms are mild. There are many things that cause hypothyroidism, and most of them can be treated with a simple medication and lifestyle modifications.

What Is the Thyroid?

The thyroid gland is an organ that helps control many processes within the body. It is found at the base of the neck, underneath the voice box or Adam’s apple, and I consider the thyroid gland to be the main metabolic hormone producer in the body.

The thyroid’s main job is to produce hormones. Hormones are messenger molecules that help different tissues communicate. When something happens in one part of the body, hormones allow a different part of the body to respond.

The thyroid gland makes three different hormones: calcitonin, T3 (triiodothyronine), and T4 (tetraiodothyronine). Calcitonin helps control levels of calcium and supports healthy bones. T3 and T4 are important for controlling growth and metabolism. When the thyroid makes T3 and T4, it travels around the body, producing many effects:

  • Cells grow and are more active.
  • The heart beats stronger and faster.
  • The nervous system is activated, leading to more focus.
  • The temperature of the body increases.
  • In children, tissues grow and become more developed.
  • The rate of metabolism (how fast the body uses up food for energy) increases.

When the thyroid gland makes too much or too little T3 and T4, many processes in the body don’t work as they should.

What Is Hypothyroidism?

Hypothyroidism occurs when the thyroid gland doesn’t make enough thyroid hormones. This condition may also be called underactive thyroid. In people with hypothyroidism, many processes in the body slow down. This condition is the opposite of hyperthyroidism, in which thyroid hormone levels get too high.

Signs and Symptoms of Hypothyroidism


Hypothyroidism can cause several different symptoms that affect different parts of the body. However, it is difficult to tell whether a person has hypothyroidism based on these signs alone. Some people with thyroid problems don’t have any symptoms, while 70% of people with a healthy thyroid have at least one of the following symptoms.

Certain symptoms tend to appear in the early stages of hypothyroidism. These include:

  • Tiredness and weakness
  • Aches and pains
  • Feeling cold when everyone else around you feels comfortable
  • Irregular or heavy periods
  • Constipation
  • Dry skin, thin hair, or brittle fingernails
  • Weight gain
  • Mood changes or depression

If hypothyroidism remains untreated, the condition can grow worse and cause additional symptoms. Signs of thyroid problems that may occur later include:

  • A hoarse voice
  • Swelling in the hands, feet, or face
  • Thickened skin
  • Problems with the senses of smell and taste
  • A drop in body temperature
  • A slow heartbeat
  • High cholesterol levels

Hypothyroidism can also lead to other health problems. If left untreated for long enough, this condition can cause a coma, although this is rare. Additionally, hypothyroidism can lead to pregnancy complications like high blood pressure, premature birth, and miscarriage.

If you notice any of these symptoms, talk to your physician. Your physician can perform a physical exam to see if your thyroid gland is larger or smaller than it should be. Additionally, your physician may recommend tests to check thyroid function. A simple blood test can measure levels of thyroid hormones. Blood tests may also be used to check levels of blood cells, cholesterol, sodium, and other hormones, and determine whether your liver and kidney are working as they should. Your doctor may also recommend imaging tests to get a better look at your thyroid and test how well it is functioning.

Causes of Hypothyroidism


Several health conditions can affect the thyroid, preventing it from making enough T3 and T4. Thyroiditis — inflammation of the thyroid — is the most common cause of hypothyroidism. During this condition, thyroid hormones leak out of the gland, making hormone levels in the body rise and then later fall. Thyroiditis can happen as a result of viral infections, including the common cold. Some people who are pregnant also develop thyroiditis.

Hashimoto’s disease is a type of thyroiditis that is a common cause of hypothyroidism. It is a disorder of the immune system. Normally, the immune system fights off germs like bacteria and viruses. In people with autoimmune disorders such as Hashimoto’s disease, the immune system attacks the body’s healthy tissues. During Hashimoto’s disease, the thyroid fills up with immune cells, which make antibodies that damage the cells of the thyroid. Women and people with other autoimmune disorders are more likely to develop Hashimoto’s disease.

Congenital hypothyroidism is a condition that is present from birth. Babies with this condition are born with a thyroid that doesn’t function normally. Over time, babies with hypothyroidism may fail to grow properly and may have intellectual disabilities. However, treatment can help a child’s body and brain develop normally.

Some medical treatments can also lead to hypothyroidism. Sometimes, people need surgery to remove some or all of the thyroid, which causes the body to make little or no thyroid hormone. Radiation therapy and some medications can also damage the cells of the thyroid, leading to hypothyroidism. Medications that can cause thyroid problems include lithium, amiodarone, and certain chemotherapy drugs.

Not eating enough iodine can also cause problems. The thyroid uses iodine as a building block to make T3 and T4 hormones. Seafood and dairy products contain iodine, and this mineral is also added to iodized salt. Using iodized salt while cooking can help most people get enough iodine to keep their thyroid functioning normally. However, people who are pregnant or eat a vegan diet may need extra iodine. On the other hand, eating too much iodine can overload the thyroid, and may also lead to hypothyroidism.

Pituitary problems can also cause hypothyroidism. The pituitary gland, located in the brain, helps control the thyroid gland. It sends signals to the thyroid using thyroid-stimulating hormone (TSH). When levels of TSH increase in the body, the thyroid gland makes more T3 and T4. Pituitary diseases or pituitary tumors can disrupt this process, leading to low levels of TSH. When the thyroid gland isn’t “told” to make more hormones, levels of T3 and T4 will drop. Pituitary problems that can lead to hypothyroidism include a pituitary adenoma (tumor), a head injury, surgery, or certain medications.

Risk Factors for Hypothyroidism

Certain factors can lead to a higher chance of developing hypothyroidism. These risk factors include:

  • Being a woman
  • Being over the age of 60
  • A family or personal history of thyroid disorders
  • Having had surgery or radiation therapy to treat the thyroid, neck, or chest
  • Having been pregnant within the last 6 months

Having other disorders also increases a person’s chances of having an underactive thyroid. Disorders that increase risk include Turner syndrome, pernicious anemia, Sjogren’s syndrome, Celiac disease, lupus, rheumatoid arthritis, and diabetes.

Treatments for Hypothyroidism


There is usually no cure for hypothyroidism. However, this condition can be kept under control with medication that helps replace low levels of thyroid hormones. People with this condition may also need to make changes to their diet.


Hypothyroidism is usually treated with a drug called Synthroid (levothyroxine). This medication is identical to the T4 hormone that is naturally made by healthy thyroid glands. Usually, people with hypothyroidism need to take levothyroxine for the rest of their life.

It may take some time to determine what dose of levothyroxine you need. Your doctor will probably start you off on a low dose, and then have you undergo a blood test 6 to 8 weeks later. You may need to adjust your dose based on the test results, and then undergo additional blood tests later. Your doctor may continue giving you blood tests every year to make sure that your current dose is working.

Make sure to continue taking levothyroxine as prescribed, even if your symptoms improve. Levothyroxine should be taken at the same time each day. Some doctors recommend taking it at night, when the body can more easily absorb it. Others suggest taking it in the morning, because it’s best to take the drug on an empty stomach. Ask your doctor what time of day is best for taking this medication. Additionally, levothyroxine can interact with some other drugs and vitamins, so ask your doctor to help you plan when to take each medication that you need.

Women who are pregnant need more thyroid hormone, because these molecules help the fetus develop. If you become pregnant while taking levothyroxine, you may need to increase your dose. But always check with your physician as your levels will need to be checked to be certain that your thyroid is perfectly in tune with your pregnancy.

Dietary Changes

Eating too much iodine may make hypothyroidism worse, particularly for people with Hashimoto’s disease. Foods like seaweed and medications such as certain cough syrups may contain high levels of iodine. Ask your doctor if you need to avoid or eat less of certain foods.


Several health conditions or treatments can harm the thyroid gland, leading it to not make enough thyroid hormones. This affects many parts of the body. Low levels of thyroid hormones cause the body and mind to slow down and use less energy. The good news is that medication often works well to keep hypothyroidism under control for life.

Articles authored by Dr. Connor are intended to facilitate awareness about health and wellness matters generally and are not a substitute for professional medical attention or advice from your own healthcare practitioner, which is dependent on your detailed personal medical condition and history. You should always speak with your own qualified healthcare practitioner about any information in any articles you may read here before choosing to act or not act upon such information.
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