Hypothyroidism

Since I know many folks with hypothyroidism, I thought I'd post some information about the disease from the National Endocrine and Metabolic Diseases Information Service:

Hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormone to meet the body’s needs. Without enough thyroid hormone, many of the body’s functions slow down. About 5 percent of the U.S. population has hypothyroidism. 1 Women are much more likely than men to develop hypothyroidism.

The thyroid gland makes two thyroid hormones, triiodothyronine (T3) and thyroxine (T4). Thyroid hormones affect metabolism, brain development, breathing, heart and nervous system functions, body temperature, muscle strength, skin dryness, menstrual cycles, weight, and cholesterol levels. A third hormone produced by specialized cells in the thyroid gland, calcitonin, affects calcium levels in the blood and the buildup of calcium in the bones. Calcitonin is not considered a thyroid hormone per se.

Thyroid hormone production is regulated by thyroid-stimulating hormone (TSH), which is made by the pituitary gland. Located in the brain, the pituitary gland is the “master gland” of the endocrine system.

Hypothyroidism has many symptoms that can vary from person to person. Some common symptoms of hypothyroidism are:

fatigue
weight gain
puffy face
cold intolerance
joint and muscle pain
constipation
dry, thinning hair
decreased sweating
heavy or irregular menstrual periods and impaired fertility
depression
slowed heart rate

How is hypothyroidism diagnosed?

Many symptoms of hypothyroidism can occur in other diseases, so hypothyroidism usually cannot be diagnosed based on symptoms alone. Health care providers take a medical history and perform a thorough physical examination. Providers may then use several tests to confirm a diagnosis of hypothyroidism and find its cause.

Thyroid-stimulating Hormone (TSH) Test

The ultrasensitive TSH test is usually the first test a doctor performs. This test is the most accurate measure of thyroid activity available.

The TSH test is based on the way TSH and thyroid hormone work together. The pituitary gland boosts TSH production when the thyroid is not making enough thyroid hormone; the thyroid normally responds to TSH by making more hormone. Then, when the body has enough thyroid hormone circulating in the blood, TSH output drops. In people who produce too little thyroid hormone, the pituitary makes TSH continuously, trying to get the thyroid to produce more thyroid hormone.

Generally, a TSH reading above normal means a person has hypothyroidism and a reading below normal means a person has hyperthyroidism.

Other Tests
Health care providers may conduct additional tests to help confirm the diagnosis or determine the cause of hypothyroidism.

The T4 test measures the actual amount of circulating thyroid hormone in the blood. In hypothyroidism, the level of T4 in the blood is lower than normal.

The thyroid autoantibody test looks for the presence of thyroid autoantibodies. Most people with Hashimoto’s disease have these antibodies, but people whose hypothyroidism is caused by other conditions do not.

How is Hypothyroidism treated?

Hypothyroidism is treated with synthetic thyroxine, which is identical to the T4 made by the thyroid. The exact dose will depend on the patient’s age and weight, the severity of the hypothyroidism, the presence of other health problems, and whether the person is taking other drugs that might interfere with how well the body uses thyroid hormone.

Health care providers test TSH levels about 6 to 8 weeks after a patient begins taking thyroid hormone and make any necessary adjustments to the dose. Each time the dose is adjusted, the blood is tested again. Once a stable dose is reached, blood tests are normally repeated in 6 months and then once a year after that.

Hypothyroidism can almost always be completely controlled with synthetic thyroxine, as long as the recommended dose is taken every day as instructed.

For more information, contact the following organizations:

American Academy of Otolaryngology—Head and Neck Surgery
1650 Diagonal Road
Alexandria, VA 22314–2857
Phone: 703–836–4444
Internet: www.entnet.org

American Association of Clinical Endocrinologists
245 Riverside Avenue, Suite 200
Jacksonville, FL 32202
Phone: 904–353–7878
Fax: 904–353–8185
Email: info@aace.com
Internet: www.aace.com

American Thyroid Association
6066 Leesburg Pike, Suite 550
Falls Church, VA 22041
Phone: 1–800–THYROID (849–7643) or 703–998–8890
Fax: 703–998–8893
Email: admin@thyroid.org
Internet: www.thyroid.org

The Endocrine Society
8401 Connecticut Avenue, Suite 900
Chevy Chase, MD 20815
Phone: 1–888–363–6274 or 301–941–0200
Fax: 301–941–0259
Email: societyservices@endo-society.org
Internet: www.endo-society.org

The Hormone Foundation
8401 Connecticut Avenue, Suite 900
Chevy Chase, MD 20815–5817
Phone: 1–800–HORMONE (467–6663)
Fax: 301–941–0259
Email: hormone@endo-society.org
Internet: www.hormone.org