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(Hashimoto's Thyroiditis; Underactive Thyroid)


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    TOP

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    TOP

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    TOP

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

Symptoms of severe or long-term hypothyroidism causes:

Diagnosis    TOP

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    TOP

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

Prevention    TOP

There are no current guidelines to prevent hypothyroidism.


American Thyroid Association
Office on Women's Health


Thyroid Foundation of Canada


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.... 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: Accessed December 15, 2017.
Last reviewed December 2017 by EBSCO Medical Review Board Marcie L. Sidman, MD
Last Updated: 12/14/2015

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