Site Map

Hypothyroidism

Myxedema; Adult hypothyroidism; Underactive thyroid; Goiter - hypothyroidism; Thyroiditis - hypothyroidism; Thyroid hormone - hypothyroidism

Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone. This condition is often called underactive thyroid.

Images

Endocrine glands
Hypothyroidism
Brain-thyroid link
Primary and secondary hypothyroidism

Causes

The thyroid gland is an important organ of the endocrine system. It is located at the front of the neck, just above where your collarbones meet. The thyroid makes hormones that control the way every cell in the body uses energy. This process is called metabolism.

Hypothyroidism is more common in women and people over age 50.

The most common cause of hypothyroidism is thyroiditis. In people with thyroiditis, swelling and inflammation damage the thyroid gland's cells.

Causes of this problem include:

Other causes of hypothyroidism include:

Symptoms

Early symptoms:

Late symptoms, if untreated:

Exams and Tests

The health care provider will do a physical exam and may find that your thyroid gland is enlarged. Sometimes, the gland is normal size or smaller-than-normal. The exam may also reveal:

Blood tests are also ordered to measure your thyroid hormones TSH and T4.

You may also have tests to check:

Treatment

Treatment is aimed at replacing the thyroid hormone you are lacking.

Levothyroxine is the most commonly used medicine:

When starting you on your medicine, your provider may check your hormone levels every 2 to 3 months. After that, your thyroid hormone levels should be monitored at least once every year.

When you are taking thyroid medicine, be aware of the following:

While you are taking thyroid replacement therapy, tell your provider if you have any symptoms that suggest your dose is too high, such as:

Outlook (Prognosis)

In most cases, thyroid hormone level becomes normal with proper treatment. You will likely take a thyroid hormone medicine for the rest of your life.

Possible Complications

Myxedema crisis (also called myxedema coma), the most severe form of hypothyroidism, is rare. It occurs when thyroid hormone levels get very, very low. The severe hypothyroid crisis is often then started by an infection, illness, exposure to cold, or certain medicines (opioids are a common cause) in people with severe hypothyroidism. It can also commonly be caused by failure to take prescribed thyroid hormone consistently or correctly.

Myxedema crisis is a medical emergency that must be treated in the hospital. Some people may need oxygen, breathing assistance (ventilator), fluid replacement, and intensive-care nursing.

Symptoms and signs of myxedema coma include:

People with untreated hypothyroidism are at increased risk of:

When to Contact a Medical Professional

Contact your provider if you have symptoms of hypothyroidism.

If you are being treated for hypothyroidism, call your provider if:

Related Information

Metabolism
Free T4 test
T3 test
Hypothalamus
Overweight
X-ray
Low blood sugar
Infertility
Miscarriage
Endoscopic thoracic sympathectomy
Iontophoresis
Thyroid gland removal - discharge

References

Brent GA, Weetman AP. Hypothyroidism and thyroiditis. In: Melmed S, Auchus RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 13.

Garber JR, Cobin RH, Gharib H, et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocr Pract. 2012;18(6):988-1028. PMID: 23246686 pubmed.ncbi.nlm.nih.gov/23246686/.

Jonklaas J, Bianco AC, Bauer AJ, et al; American Thyroid Association Task Force on Thyroid Hormone Replacement. Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association task force on thyroid hormone replacement. Thyroid. 2014;24(12):1670-1751. PMID: 25266247 pubmed.ncbi.nlm.nih.gov/25266247/.

BACK TO TOP

Review Date: 8/12/2022  

Reviewed By: Sandeep K. Dhaliwal, MD, board-certified in Diabetes, Endocrinology, and Metabolism, Springfield, VA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

ADAM Quality Logo
Health Content Provider
06/01/2025

A.D.A.M., Inc. is accredited by URAC, for Health Content Provider (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics. This site complied with the HONcode standard for trustworthy health information from 1995 to 2022, after which HON (Health On the Net, a not-for-profit organization that promoted transparent and reliable health information online) was discontinued.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2024 A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

A.D.A.M. content is best viewed in IE9 or above, Firefox and Google Chrome browser.