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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 happens when the thyroid gland does not produce enough thyroid hormone. The most common form of hypothyroidism is Hashimoto's thyroiditis.
Thyroid Gland
thyroid gland male
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Causes

Hashimoto's thyroiditis occurs when the immune system produces antibodies that attack cells of the thyroid gland. This causes thyroid swelling and loss of function. Other causes include:
  • Idiopathic thyroid atrophy—destruction of thyroid tissue for unknown reasons
  • Iodine deficiency—when a thyroid gland needs iodine to produce thyroid hormone (rare in the United States)
  • Subacute thyroiditis—following a viral upper respiratory tract infection
  • Medical treatments— radiation to the head and neck or surgical removal of the thyroid gland (called subtotal thyroidectomy )
  • Medicines (such as lithium , iodine, amiodarone , interleukins)
  • Certain diseases (such as cancer or infection)
  • Pituitary adenoma —benign tumor of the pituitary gland

Risk Factors

Risk factors that can increase your chance of developing hypothyroidism include:

Symptoms

Years may pass before you notice symptoms.
Symptoms include:
  • Fatigue
  • Weakness
  • Coarse, brittle hair; hair loss
  • Facial puffiness
  • Dry skin
  • Swollen hands or feet
  • Cold intolerance
  • Weight gain
  • Constipation
  • Achy feeling all over
  • Depression and irritability
  • Memory loss
  • Difficulty concentrating
  • Blurred vision
  • Menstrual abnormalities or infertility
Symptoms of severe or long-term cases include:
  • Coma
  • Slow heart rate
  • Depressed breathing
  • Hypothermia (low body temperature)

Diagnosis

The doctor will ask about your symptoms and medical and family history. A physical exam will be done. To confirm the diagnosis, blood tests will be done, which include:
  • Thyroid stimulating hormone (TSH)
  • Free T4 and total T3
  • Antibodies that attack the thyroid gland

Treatment

There is no specific treatment in the early stages of Hashimoto's thyroiditis. But, in most cases, you will end up developing hypothyroidism. Treatment involves taking medicine to replace the thyroid hormones (such as levothyroxine , triiodothyronine).

Prevention

There are no known ways of preventing hypothyroidism.

RESOURCES

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

Women's Health.gov http://www.hrsa.gov/about/organization/bureaus/owh/index.html

CANADIAN RESOURCES

Canadian Institute for Health http://www.cihi.ca

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

References

American Association of Clinical Endocrinologists. AACE medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism. Endocrine Practice . 2002;8:457-469.

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;90:4946-4954.

Hypothyroidism. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed . Updated November 19, 2012. Accessed November 20, 2012.

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

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

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

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