Causes and Risk Factors of Thyroid Disease

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The thyroid is a butterfly-shaped gland in the front of the neck. Its primary function is to produce the hormones triiodothyronine (T3) and thyroxine (T4). These hormones travel through the body and help regulate metabolism. They also aid in brain development, digestive function, muscle control, and balancing mood.

When the thyroid produces either too much or too little of these hormones, it causes the gland to work improperly, leading to disorders such as hyperthyroidism and hypothyroidism, the two most common types of thyroid disease.

Types of Thyroid Disease
Verywell / Emily Roberts 

Common Causes

In the case of hyperthyroidism, the thyroid is overproducing thyroid hormones. This can happen due to inflammation in the thyroid, called thyroiditis, which causes the thyroid to create excess hormones.

Hyperthyroidism can also be caused by nodules that are known as toxic adenomas, which develop on the gland and start secreting hormones in addition to the hormones produced by the thyroid. In rare cases, hyperthyroidism can be caused by a pituitary gland dysfunction or cancerous growth on the thyroid that can disrupt the hormonal balance and production of T3 and T4.

Autoimmune disorders such as Graves' disease can also cause hyperthyroidism.

For hypothyroidism and the diseases associated with it, the thyroid isn’t producing enough thyroid hormone, which also results in a lack of energy. Causes of hypothyroidism include an autoimmune disorder such as Hashimoto’s disease. This is a condition in which the body attacks the thyroid and causes it to produce fewer thyroid hormones.

Hypothyroidism can also be a result of exposure to high amounts of radioactive iodine from hyperthyroidism treatment, which then results in permanent hypothyroidism.

Hypothyroidism could also be a side effect of radiation therapy used to treat cancers in the head and neck. Pregnancy can also cause hypothyroidism, as well as a congenital defect from birth in which the thyroid does not develop properly.


Conditions like Hashimoto’s disease and Graves' disease can be hereditary. Aside from family history, there are several other risk factors for both hypothyroidism and hyperthyroidism, some of which (including gender and pregnancy) overlap.

Hypothyroidism Risk Factors
  • Age and gender (women over 60 at high risk)

  • Preexisting condition (autoimmune disease such as type 1 diabetes or celiac)

  • Pituitary gland disorder

  • Pregnancy (women who are pregnant or who have had a baby in the past six months at high risk)

Hyperthyroidism Risk Factors
  • Gender (females at higher risk)

  • Family or personal history of autoimmune disorders (celiac, lupus, rheumatoid arthritis)

  • Past trauma to thyroid gland

  • Current or recent pregnancy

  • Smoking

  • Recent use of iodine contrast (such as that used in CT scans)

Lifestyle Risk Factors

Lifestyle risks for hyperthyroidism.
Cindy Chung / Verywell 

There are certain lifestyle factors that increase the risk of thyroid disorders. They include:

  • Smoking, as tobacco contains substances that affect the thyroid gland, causing inflammation and interfering with the absorption of iodine as well as the production of thyroid hormones.
  • Psychological stress such as a divorce or dealing with the loss of a friend or family member.
  • Injury or trauma to the thyroid.
  • History of certain medication use in high amounts, such as lithium (used in many mood stabilizers) and iodine.

One of the biggest hurdles in diagnosing thyroid disease is that its symptoms are common among many different types of diseases. One of the most important steps to take if you think you might have an issue with your thyroid is to get blood work done. This will show the levels of thyroid hormones in your bloodstream and could be an important step to properly diagnosing and treating your condition.

A Word From Verywell

If you have any of the conditions that put you at high risk for thyroid disease, you should have your thyroid checked by your healthcare provider periodically. If you are having any increased symptoms related to your condition, be sure to notify your healthcare provider as well. There are many risk factors and causes for thyroid disease, but early diagnosis and treatment is crucial in thyroid disease and most health conditions.

read how yeast infections and thyroid disease could be linked.

Frequently Asked Questions

  • What is autoimmune thyroid disease?

    It’s when your immune system mistakenly attacks your thyroid, a gland that produces hormones that control a variety of bodily systems and functions. The two common types of autoimmune thyroid disease are Hashimoto’s thyroiditis, which results in too little hormone, and Graves’ disease, which results in an overproduction of hormone.

  • Why are women at greater risk of thyroid disease?

    Thyroid diseases are often caused by autoimmune diseases, which are more common among women. In addition, the female hormone estrogen increases the production of thyroid-binding globulin, which will increase thyroid hormone requirements in patients who are on thyroid hormone treatment. As a result, problems often arise when estrogen balance changes, such as in pregnancy or menopause.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Hennessey JV. Subacute Thyroiditis. South Dartmouth, MA:, Inc.; 2000.

  2. National Institute of Diabetes and Digestive and Kidney Diseases. Graves' Disease. Sept 1, 2017.

  3. National Institute of Diabetes and Digestive and Kidney Diseases. Hashimoto's Disease. Sept 1, 2017.

  4. Feen rønjom M. Radiation-induced hypothyroidism after treatment of head and neck cancer. Dan Med J. 2016;63(3)

  5. Anaya JM, Shoenfeld Y, Rojas-Villarraga A. Autoimmunity: From Bench to Bedside [Internet]. Bogota, Columbia: El Rosario University Press; 2013.

  6. Kim SJ, Kim MJ, Yoon SG, et al. Impact of smoking on thyroid gland: dose-related effect of urinary cotinine levels on thyroid function and thyroid autoimmunity. Sci Rep. 2019;9(1):4213. doi:10.1038/s41598-019-40708-1

  7. Kibirige D, Luzinda K, Ssekitoleko R. Spectrum of lithium induced thyroid abnormalities: a current perspective. Thyroid Res. 2013;6(1):3. doi:10.1186/1756-6614-6-3

Additional Reading

By Colleen Travers
Colleen Travers writes about health, fitness, travel, parenting, and women’s lifestyle for various publications and brands.