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.
Many of the symptoms that occur when the body is functioning at an increased rate are the same symptoms one might experience, for example, during a panic attack, including nervousness, increased perspiration and an irregular heartbeat. Also, women with hyperthyroidism may experience light, infrequent periods, or may stop menstruating altogether. They may also experience problems with infertility and miscarriage.
Who Is Most At Risk?
Women are five to eight times more likely to suffer from a thyroid disorder than men. In fact, one in eight women will develop a thyroid disorder in their lifetimes. Approximately five to eight percent of women develop thyroid problems shortly after giving birth.
Women continue to have a higher risk of developing a thyroid disorder with age, but men's risk also increases as they pass age 60. The Thyroid Foundation of America recommends that women receive annual thyroid hormone level tests starting at age 50, and that men take them starting at age 60.
They also recommend that anyone with a family history of testing positive for thyroid disease or other autoimmune disorders should have their thyroid function evaluated every five years after the age of 35.
The American Cancer Society estimates that in 2001 there will be 19,500 new cases of thyroid cancer diagnosed in the United States with 14,900 cases occurring in women and 4,600 cases in men.
Radiation exposure during childhood increases the risk of thyroid cancer if the exposure involved the head and neck region, and it was done at therapeutic, rather than diagnostic, doses. Frequent exposure to head-neck irradiation was commonplace in the past, when X-rays were used as therapeutic treatment for conditions like acne, fungal infections of the scalp, enlarged thymus glands. They were also used to shrink tonsils.
These procedures that used X-rays for therapeutic purposes are no longer performed. Current X-ray use is for diagnostic purposes, like dental films, and it involves minimal radiation exposure. It has also been noted that children who lived near the site of the 1986 Chernobyl nuclear plant accident have an increased occurrence of thyroid cancer.
The National Cancer Institute recommends that anyone who has received such therapeutic doses of radiation to the head or neck should be examined by a doctor every one to two years. The doctor should perform a careful exam of the neck to check for lumps in the thyroid gland or any enlargement of nearby lymph nodes. Check Out Symptoms
According to statistics from the Thyroid Foundation of America, nearly 9.6 million Americans with a thyroid disorder are unaware that they are ill. That's nearly half the number of Americans who suffer from it. This is partly because many of the signs and symptoms of thyroid dysfunction are non-specific.
Some of those symptoms include fatigue, changes in weight, low mood and forgetfulness. If you are experiencing any of the symptoms, check with a doctor. Doctors can provide a definitive diagnosis with a simple blood test to measure the levels of the thyroid hormones TSH, T-4 and T3.
What Are the Treatments?
The treatment for hypothyroidism involves increasing the body's own thyroid hormone supply with a hormone supplement. The most popular thyroid medication is Synthroid, which contains as a basic component a compound called levothyroxine.
There were some concerns earlier this summer when the FDA threatened to pull Synthroid off the market because of an expired FDA clearance. But it is available in different forms, including the generic form called Levothroid and Levoxyl. The current treatment of choice for hyperthyroidism in the United States is radioactive iodine ablation.
For more information on thyroid disease go to The Thyroid Foundation of America Web site.