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Hypothyroidism (underactive thyroid) is a thyroid disorder that affects many people. But what is it and what does it mean for your overall health? 

At Banner Health, we’re here to help you understand hypothyroidism better and make decisions about your thyroid health. Learn about what causes it, its symptoms and how it can be treated. 

What is hypothyroidism?

The thyroid is a small butterfly-shaped gland in your neck that plays an important role in how your body uses energy, a process called metabolism. It controls your metabolism by making hormones called T3 (triiodothyronine) and T4 (thyroxine). These hormones also help maintain your body temperature and keep your organs (like your heart and brain) and muscles working well.

Hypothyroidism happens when your thyroid does not make enough of these hormones, which slows down your metabolism.

How is hypothyroidism different from hyperthyroidism?

Imagine your thyroid hormones as tiny messengers that tell your body how fast or slow to do things. Hypothyroidism and hyperthyroidism are the opposite extremes.

Hypothyroidism is when your thyroid does not make enough of these important hormones, so your metabolism slows down. Hyperthyroidism is the opposite – there are too many thyroid hormones and your body speeds up. 

What are the symptoms of hypothyroidism?

When you have hypothyroidism, your body generally feels like it’s slowing down. Symptoms are different for each person and you may not notice them at first. Over time, symptoms will get worse. 

The most common signs and symptoms include:

  • Feeling very tired (fatigued)
  • Unexplained weight gain
  • More sensitive to cold
  • Constipation
  • Dry skin and hair
  • Puffy face
  • Hoarse voice
  • Thinning hair
  • Muscle aches and joint pain
  • Depression
  • Memory problems
  • Irregular menstrual periods
  • Swollen thyroid gland (goiter) 

Along with these symptoms, children and young adults with hypothyroidism may also have delayed growth and development (puberty), as well as difficulty concentrating and memory concerns, which can lead to problems with school performance.

What causes hypothyroidism?

There are many reasons why the thyroid gland does not make enough thyroid hormone. 

The most common cause of hypothyroidism is an autoimmune disorder called Hashimoto’s thyroiditis. This disorder happens when the immune system attacks the thyroid gland, causing it to not work as it should. 

Other causes of hypothyroidism include:

  • Thyroid surgery or radioactive iodine treatment: Sometimes, people need surgery to remove part or all of their thyroid gland. Others receive radioactive iodine treatment for their thyroid problems. 
  • Radiation therapy: If you’ve had radiation therapy near your neck, it can damage your thyroid and lead to hypothyroidism.
  • Medications: Certain medications, like those used to treat heart problems or mental health conditions, can affect thyroid hormone production.

Some less common causes of hypothyroidism include:

  • Iodine deficiency: Your body needs iodine to make thyroid hormones. A lack of iodine in your diet can lead to thyroid problems.
  • Congenital hypothyroidism: Some babies are born with an underactive thyroid gland. 
  • Pituitary disorders: A rare cause of hypothyroidism is when the pituitary gland does not make enough thyroid-stimulating hormone (TSH). TSH tells the thyroid how much thyroid hormone to make. 
  • Pregnancy: Hypothyroidism can also happen during or after pregnancy. Not treating it during pregnancy can increase the chances of complications like miscarriage, premature birth and preeclampsia. Untreated hypothyroidism can also be harmful to the baby. 

Am I at risk for hypothyroidism?

You may be more likely to have hypothyroidism if you:

  • Are older than age 60
  • Have an autoimmune disease, like type 1 diabetes or rheumatoid arthritis
  • Have a family history of thyroid problems
  • Have been treated with radioactive iodine or anti-thyroid medicines
  • Had thyroid removal surgery
  • Have iodine deficiency
  • Received radiation on your neck or upper chest

How is hypothyroidism diagnosed?

If you have symptoms, talk to your health care provider. Hypothyroidism can look like other health problems, so sharing your concerns is important.

Your provider will do a physical exam, review your medical history and may order a series of blood tests to measure the amount of thyroid hormone and TSH in your blood. 

Before having blood tests, tell your provider about any medicines or supplements you are taking because these can affect the results. This includes tyrosine, biotin, kelp and bladderwrack.

How is hypothyroidism treated?

Hypothyroidism can be managed with a daily medication called levothyroxine. This medication replaces the missing hormones in your body, helping you feel better and reducing symptoms.

You may need to take medication for the rest of your life. Your provider may also need to change the dose over time to make sure your medication works correctly.

It’s important to talk to your provider about any foods, medications or supplements you take before starting thyroid medication. Things like antibiotics, antacids, iron, calcium, fiber and soy products can affect your body’s ability to absorb levothyroxine if taken at the same time as your thyroid medication.

Do thyroid medications have side effects?

Levothyroxine does not usually have any side effects since it is just replacing a hormone your body needs. However, side effects can happen if you take too much medicine. This can lead to issues like sweating, shaky hands, headaches, diarrhea and vomiting. 

If you notice new symptoms while taking levothyroxine, talk to your provider. Make sure to let them know if your symptoms get worse or don’t get better. Rarely, too much thyroid hormone in your body can cause a thyroid storm. If you notice fast or irregular heartbeats (palpitations) or a high fever, call 911.

What can happen if hypothyroidism is not treated?

Hypothyroidism can become more severe and potentially life-threatening if left untreated for a long time. It can strain your heart and increase cholesterol levels, raising your risk of heart problems. Untreated hypothyroidism can also affect your mental health, make it harder to get pregnant and increase the risk for birth defects if left untreated during a pregnancy.

What is the long-term outlook for hypothyroidism?

Hypothyroidism is a lifelong condition, but most people can lead healthy lives with early diagnosis, treatment and monitoring. 

Here are some steps you can take:

  • Iodine in your diet: Eat foods with iodine, like seafood, eggs and dairy products, or use iodized salt to help your thyroid work properly.
  • Stay healthy: Eat well, exercise regularly, maintain a healthy weight and manage stress. These things are good for your overall health, including your thyroid. Quit smoking and limit alcohol.
  • Take medication as prescribed: It’s important to take your medication every morning, exactly as your provider tells you to do. This keeps your thyroid working well and helps you stay healthy.
  • Check your thyroid regularly: Work closely with your health care team to ensure your thyroid health remains stable.

Schedule an appointment

Take control of your thyroid health today by scheduling an appointment with one of our endocrinology specialists at Banner Health. Start your journey toward a healthier life.