The thyroid gland is a small butterfly-shaped
structure located in the front of the neck. Hypothyroidism (low thyroid function) occurs when the thyroid gland does not produce
enough of a substance called thyroid hormone, which
helps to regulate the body's metabolism. Hypothyroidism develops in about
5% of the population in the United States and is especially common in women
older than 60 years. The December 10, 2003, issue of JAMA includes an article about treating hypothyroidism.
Hashimoto's thyroiditis is the most common
cause. In this condition, the body's immune system attacks the thyroid gland
and causes the production of thyroid hormone to decrease.
Treatments for certain thyroid diseases can damage the thyroid
gland, especially radioactive iodine that is often
used to treat an overactive thyroid (hyperthyroidism).
Surgery to remove most or all of the gland, usually done when there is a thyroid
tumor, will also cause hypothyroidism.
Certain drugs can cause hypothyroidism, particularly lithium and the heart medication amiodarone.
Sometimes the thyroid gland does not produce enough thyroid hormone
because the pituitary gland near the brain is not
functioning properly. The pituitary gland signals the thyroid gland to produce
thyroid hormone through the production of thyroid-stimulating
hormone or TSH.
Weight gain (usually no more than 10 to 15 pounds) and difficulty
Dry hair and skin
Decreased sex drive
Patients with mild hypothyroidism may not have any symptoms.
In some people, the thyroid gland may enlarge in an effort to produce
the thyroid hormone that the body needs and become visible in the neck, forming
what is known as a goiter.
In most cases, hypothyroidism is easily diagnosed with a blood test
that measures levels of TSH and thyroid hormone in the blood. An endocrinologist (a doctor who specializes in glands and hormones) may
be helpful in evaluating the cause and determining treatment options.
Hypothyroidism is usually easy to treat with a once-a-day pill containing
synthetic thyroid hormone. However, blood tests and several visits with a
physician may be needed to determine the correct dosage. The benefits of treatment
may not be apparent for a month or longer.
American Thyroid Association 800/THYROID (849-7643)http://www.thyroid.org
Thyroid Foundation of America 800/832-8321http://www.allthyroid.org
To find this and other JAMA Patient Pages, go to the Patient Page link
on JAMA's Web site at http://www.jama.com.
Sources: American Thyroid Association, National Institute of Diabetes
& Digestive & Kidney Diseases, American Foundation of Thyroid Patients,
Thyroid Foundation of America
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TOPIC: THYROID DISORDERS
Parmet S, Lynm C, Glass RM. Hypothyroidism. JAMA. 2003;290(22):3024. doi:10.1001/jama.290.22.2914