Carl R. Darnall Army Medical Center - Health Library

Hypothyroidism

(Hashimoto's Thyroiditis; Underactive Thyroid)

Definition

The thyroid gland is a butterfly-shaped gland in the front of the neck. It makes hormones that control metabolism. Hypothyroidism is when the thyroid does not make enough thyroid hormone.

Thyroid Gland
thyroid gland male

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Causes ^

Hypothyroidism may be caused by damage or injury to the thyroid. This may happen with:

  • Disorder of the immune system
  • Congenital defects of the gland or how it works
  • Surgery, medical procedures, or radiation therapy for thyroid treatment

It may also be caused by:

  • Problems with pituitary glands that sends signal to the thyroid
  • Iodine deficiency—rare in the US, iodine is needed to make thyroid hormones

In some people, the cause may remain unknown.

Risk Factors ^

Hypothyroidism is more common in women. It is also more common in those aged 65 years and older. Other factors that may increase your chance of hypothyroidism include:

Symptoms ^

Symptoms may not always appear. In those that have symptoms, hypothyroidism may cause:

Symptoms of severe or long-term hypothyroidism causes:

Diagnosis ^

You will be asked about your symptoms and medical history. A physical exam will be done.

A blood test may be done to check levels of thyroid stimulating hormone (TSH), and/or free T4. Other tests may be recommended to rule out health conditions that are similar to hypothyroidism.

Treatment ^

Medicine can be used to make up for the missing thyroid hormones. The amount of medicine needed may change over time.

Prevention ^

There are no current guidelines to prevent hypothyroidism.

RESOURCES:

American Thyroid Association
https://www.thyroid.org

Office on Women's Health
https://womenshealth.gov

CANADIAN RESOURCES

Health Canada
https://www.canada.ca

Thyroid Foundation of Canada
http://www.thyroid.ca

REFERENCES:

Escobar-Morreale HF, Botella-Carretero JI, Escobar del Rey F, et al. Treatment of hypothyroidism with combinations of levothyroxine plus liothyronine. J Clin Endocrinol Metab. 2005;90(8):4946-4954.

Hypothyroidism in adults. EBSCO DynaMed Plus website. Available at:http://www.dynamed.com/topics/dmp~AN~T115914/Hypothyroidism-in-adults. Updated November 27, 2017. Accessed December 15, 2017.

Roberts CG, Ladenson PW. Hypothyroidism. Lancet. 2004;363(9411):793-803.

Surks MI, Ortiz E, Daniels GH, et al. Subclinical thyroid disease: scientific review and guidelines for diagnosis and management. JAMA. 2004;291(2):228-238.

Thyroid hormone treatment. American Thyroid Association website. Available at: https://www.thyroid.org/thyroid-hormone-treatment. Accessed December 15, 2017.

Last reviewed December 2017 by EBSCO Medical Review Board Marcie L. Sidman, MD  Last Updated: 12/14/2015