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Hypothyroidism Facts

  • Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormone.
  • Thyroid hormones affect the metabolic processes of the body.
  • Hypothyroidism can be caused by conditions of the thyroid as well as other disease which may indirectly affect the thyroid.
  • Women are affected by hypothyroidism more than men, especially as they age.
  • The incidence of hypothyroidism increases significantly in the elderly.
  • Low thyroid hormone levels decrease metabolism (how energy is used), and increase the risk of other health issues such as heart disease and problems of pregnancy.

What Causes Adults Hypothyroidism?

Common causes of hypothyroidism in adults include:

Autoimmune Thyroiditis (Hashimoto's Thyroiditis)

This inherited condition is the most common cause of hypothyroidism in adults. Hashimoto's thyroiditis is an autoimmune disease in which the body's immune system, or natural defense system, attacks its own thyroid gland. This causes a thyroid enlargement or goiter and progressive thyroid destruction.

Subacute Thyroiditis (inflammation of the thyroid gland after a viral disease or after a pregnancy)

In this condition there is usually a phase of hyperthyroidism (a condition in which the thyroid produces an excess of thyroid hormones) followed by a hypothyroid phase. Eventually thyroid function returns to normal. The three types of subacute thyroiditis are:

  1. subacute granulomatous thyroiditis, also referred to as painful thyroiditis;
  2. subacute painless thyroiditis, which is silent and also referred to as lymphocytic thyroiditis; and
  3. postpartum thyroiditis.

Previous Thyroid Therapy

Surgical removal of the thyroid gland may be performed to treat thyroid nodules, hyperthyroidism, or other conditions. Treatment of hyperthyroidism with radioactive iodine also results in destruction of thyroid tissue and may lead to hypothyroidism.

Drug-induced Hypothyroidism

Taking some prescription medications may alter thyroid function. These include lithium (Eskalith, Lithobid) and amiodarone (Cordarone).

Pituitary and Hypothalamic disease

Both the hypothalamus and pituitary gland are involved in the signaling pathways that control the function of the thyroid gland. Diseases of the hypothalamus and pituitary gland can, therefore, affect the amount of thyroid hormone made and secreted by the thyroid gland. Hypothyroidism due to pituitary disease is termed "secondary hypothyroidism," while hypothyroidism due to hypothalamic disease is termed "tertiary hypothyroidism."

Iodine deficiency

Iodine deficiency does not occur in the U.S.. Only severe iodine deficiency will cause low thyroid hormone levels. This condition may occur in mountainous areas of poor, less industrialized nations. Mild to moderate iodine deficiency is common in many European countries.

Medically Reviewed by a Doctor on 11/20/2017
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Questions to Ask Your Doctor About Thyroid Disease

Note: We recommend you use this page as a reference for your consultation with your doctor.

1. Are my symptoms consistent with thyroid disease?

2. Could my symptoms be the result of anything else?

3. What investigations do I need to have performed to make a diagnosis?

4. How safe are these investigative tests and procedures?

5. What exactly is a thyroid biopsy, and how is it performed?

6. If I do have thyroid disease, how do we treat it?

7. If I need medications, what are the potential side effects?

8. If I need medication, is there any special way I should be taking it?

9. Do we need to monitor blood levels for thyroid function? If so, how often?

10. Is there a possibility my thyroid disease will require surgery?

eMedicineHealth Reminder: Establishing an accurate diagnosis is key to proper treatments. You are the most important person in this process by accurately describing to your doctor the character, location, duration, and time of onset of your symptoms. You should also inform your doctor about vitamins, herbs, and medications you are taking.

Read What Your Physician is Reading on Medscape

Hypothyroidism »

Hypothyroidism is a common endocrine disorder resulting from deficiency of thyroid hormone.

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