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Hypothyroidism

(Hashimoto's Thyroiditis; Underactive Thyroid)

Definition

The thyroid gland is a butterfly-shaped gland in the front of the neck. It produces hormones that control metabolism. Hypothyroidism results when the thyroid gland doesn't produce enough thyroid hormone. The most common form of hypothyroidism is Hashimoto thyroiditis.
Thyroid Gland
thyroid gland male
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Causes

Hashimoto thyroiditis is an autoimmune disorder. The immune system produces antibodies that attack cells of the thyroid gland.
Hypothyroidism may also be caused by:

Risk Factors

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

Symptoms

You may not have symptoms of hypthyroidism. 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.
Tests may include blood tests 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

Thyroid replacement therapy involves taking medications that replace the function of the thyroid gland. This therapy may also prevent cancer cell growth in people who had surgery or radiation treatment for thyroid cancer.
People with Hashimoto thyroiditis are monitored as long as they have normal thyroid function and remain symptom-free. Once function decreases or symptoms appear, treatment is started with thyroid replacement therapy.

Prevention

There are no current guidelines to prevent hypothyroidism.
The American Academy of Pediatrics and United States Preventive Services Task Force recommend screening all newborns for congenital hypothyroidism. If you are at high risk for developing hypothyroidism, talk to your doctor about annual screening.

RESOURCES

The American Thyroid Association http://www.thyroid.org

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

CANADIAN RESOURCES

Canadian Institute for Health Information http://www.cihi.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 website. Available at: http://www.ebscohost.com/dynamed. Updated October 21, 2015. Accessed December 14, 2015.

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: http://www.thyroid.org/thyroid-hormone-treatment. Accessed December 14, 2015.

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