It makes its nearly 15 million sufferers feel tired and nervous, irritable, and sleepless, and it can make them lose weight.
Half of those who are afflicted with thyroid disease don't even know they have it, attributing its symptoms to unrelated issues such as aging, menopause or depression.
In fact, many people know little about the thyroid, including where the thyroid gland is located, or what it does. So ABCNEWS' Dr. Nancy Snyderman presented the facts about thyroid disease on Good Morning America.
What Exactly Is the Thyroid?
The thyroid is a small, butterfly-shaped gland that sits at the back of the neck below the Adam's apple and wraps around the windpipe. It produces thyroid hormones that control the metabolism, or the rate at which the body's cells go about their business.
The thyroid gland affects the functioning rate of every cell in the body. Thyroid hormones influence every organ, tissue and cell in the body. They also control heart rate, body weight, body temperature, energy level, muscle strength and menstrual regularity.
When the thyroid malfunctions, it can do so in one of two ways. It can produce too little thyroid hormone, a condition known as hypothyroidism, which causes the body to function at a lower rate. Or, it can produce too much hormone, known as hyperthyroidism, which speeds up the rate at which each cell functions. Both conditions can result in troublesome symptoms.
What Is Hypothyroidism? Hypothyroidism, the most common type of thyroid disease, affects 11 million Americans. It is estimated that nearly 10 to 15 percent of those diagnosed with depression actually have a thyroid hormone deficiency.
The symptoms it shares with depression include fatigue, memory loss and difficulty concentrating. But the distinguishing symptoms of hypothyroidism are: coarse, dry skin and hair, intolerance to cold and constipation. A blood test can determine if it is hypothyroidism.
Hypothyroidism can also contribute to heart disease. One prominent side effect of a low level of thyroid hormone is an increased amount of LDL cholesterol circulating in the blood.
LDL is the so-called "bad" cholesterol, known to build up inside blood vessels. People whose hypothyroidism goes untreated can develop permanent damage to the coronary vessels of the heart. It can also damage other vessels throughout the body.
Therefore, some doctors recommend that all patients with high cholesterol levels, a condition known as hypercholesterolemia, have their thyroid function tested. Simply prescribing a thyroid supplement to these patients to control the hypothyroidism will resolve the associated cholesterol problem, and decrease the risk of heart disease.
What Is Hyperthyroidism?
Someone with hyperthyroidism might experience any or all of the following symptoms: nervousness, decreased menstrual flow, weight loss, and irregular heartbeat.
An excess of thyroid hormone results in an increased metabolism, or a speeding up of all reactions that occur in the body. Many of the people who chalk their symptoms up to a case of nerves may actually suffer from hyperthyroidism.