Thyroid Disease Hypothyroidism (low thyroid hormone) Hyperthyroidism (high thyroid hormone) Two major types of thyroid disease... If your doctor says you are "hypothyroid," it means you have a fairly common chronic medical condition: Your thyroid produces too little thyroid hormone. Fortunately, hypothyroidism can be treated easily, effectively, inexpensively and painlessly. On the other hand, if your doctor tells you that you are "hyperthyroid," your have the opposite problem: Your thyroid gland produces too much thyroid hormone. The most common type of hyperthyroidism, Graves' disease, is the disorder that afflicts First Lady Barbara Bush. Both hypothyroidism and hyperthyroidism are caused by improper functioning of the thyroid, a gland located in the front of the neck, just below the Adam's apple. The thyroid gland produces hormones that affect most organs, including the heart, brain, liver, kidneys and skin. Wide variety of symptoms.... Because thyroid hormone affects virtually every cell in your body, you may suffer from a wide spectrum of complaints if you have thyroid disease. If your thyroid produces too little thyroid hormone, your heartbeat may be slowed and you may feel tired, depressed and run down. Your skin, hair and fingernails may grow more slowly, so that they become rough, dry and brittle. You may be overly sensitive to cold temperatures. Other signs and symptoms of hypothyroidism include constipation, anemia, fatigue, loss of appetite, slight increases weight, irregular or absent menstrual periods, swollen ankles, puffiness about the face, elevated cholesterol and, possibly, hypertension. If, however, your thyroid produces too much hormone, you may experience a fast, pounding heartbeat -- even at rest, and you may lose weight even if your diet and appetite have not changed. Other symptoms of hyperthyroidism include frequent bowel movements, inability to sleep, nervousness, muscle weakness and fine tremors of the fingers and tongue. Many causes... Thyroid disease has many different causes. In the United States, the most common cause of hypothyroidism is Hashimoto's disease, a condition in which the body inexplicably begins treating the thyroid as if it were a "foreign" tissue -- and injures it. As the damaged thyroid gland produces less and less hormone, the pituitary gland secretes another hormone, thyroid stimulating hormone (TSH), to try to encourage the thyroid to work harder. This increased demand on the thyroid may cause it to enlarge -- creating what is commonly known as a "goiter." Hypothyroidism may also develop in people who have had surgical or radioactive iodine treatment for an overactive thyroid, or who have received high doses of radiation for cancers of the head and neck. Radiation treatments to the head or neck, quite commonly administered to children between 1920 and 1960 for enlarged thymus, acne or other non-thyroid related problems, may also increase the risk of hypothyroidism. Sometimes, infants are born without a thyroid gland or with a gland that does not function normally. These children must be treated for their hypothyroidism immediately -- and for life -- if they are to develop normally. Affects millions, especially women.... Thyroid disease, particularly hypothyroidism, is a fairly common medical condition. It is difficult to estimate how many people are hypothyroid, since many individuals are hypothyroid without knowing it. Researchers estimate that at least 6 to 7 million Americans are hypothyroid -- but only on-half have been diagnosed. Most of the remainder feel varying degrees of discomfort or lethargy and often incorrectly attribute such symptoms to normal aging. Another 1 million Americans are hyperthyroid. Hypothyroidism primarily affects women -- it is about four times more common in women than in men -- but can occur in either sex and at any age. It affects older people more often than younger people and is most common in women over the age of 50. In the United States, it is estimated that less than 1% of young people are hypothyroid, whereas up to 10% of the elderly are affected. Hyperthyroidism, too, is more common in women, most often affecting those in their 30s and 40s. Confirmed by simple blood test... In the past, hypothyroidism could not be detected until it was fairly advanced. Today, however, sophisticated ne laboratory tests enable hypothyroidism to be detected earlier. One such test, the sensitive TSH assay, measures how much TSH is circulating in the blood. If the TSH assay shows that you have a high level of TSH, this means that your pituitary gland is sensing that your thyroid is not making enough thyroid hormone to meet its needs. Thus, you are hypothyroid. Treatment critical to good health... It is important to treat both hypothyroidism and hyperthyroidism, because if left untreated, these diseases can have serious consequences. The risks of not treating hypothyroidism differ depending on the affected individual. In newborns who cannot make enough thyroid hormone prompt treatment is crucial in preventing mental retardation, delayed growth, facial deformities and other severe abnormalities. That is why all newborns undergo thyroid screening ar birth. Children and adolescents who become hypothyroid also risk abnormal mental and physical development it they are not treated promptly. In adults, the consequences of untreated hypothyroidism are usually less severe but may still cause considerable discomfort or disability. If severe hypothyroidism goes untreated in an adult, mental illness or heart disease may result. Of even greater importance, severe, untreated hypothyroidism can result in death. Left untreated, hyperthyroidism can also have serious effects. For example, certain tissues, particularly those behind the eyeball, can thicken. If the condition remains untreated, this abnormal tissue behind the eye can push the eyeball forward in the socket, producing a wide-eyed appearance that can threaten vision. In advanced cases of untreated hyperthyroidism, a life-threatening metabolic condition known as "thyroid storm" can occur. Thyroid disease: Treatable, not curable... Since most cases of hypothyroidism result from either permanent destruction or abnormality of the thyroid gland, the condition cannot be cured. However, it can be treated easily and inexpensively with a synthetic thyroid hormone called levothyroxine. Levothyroxine, which works in the body exactly the way natural thyroid hormone does, must be taken daily for life by the vast majority of hypothyroid patients. Precise dosage. The amount of thyroid hormone replacement that patients require varies, and many tablet strengths are available. Since your physician uses sensitive blood tests to determine the dosage that is best for you, it is important to follow your physician's instructions and take the proper dosage of levothyroxine every day. Slow, gradual improvement in hypothyroidism. The symptoms of hypothyroidism do not disappear as soon as you begin taking thyroid hormone. However, if you remain patient and continue to take the medication as directed, you will notice a slow and gradual improvement in your appearance and well being. Even if you are severely hypothyroid, a few months of treatment should relieve all of your hypothyroid-related symptoms. But feeling better does not mean that you can stop taking thyroid hormone! Even though your symptoms have subsided, it is important to continue to take your medicine. The tablets you take replace a hormone your thyroid no longer makes in sufficient quantities. If you stop taking the medication, your body will take about a month to use up the majority of hormone you have already taken. Then, over the following weeks, your old symptoms will gradually return. Hyperthyroidism treatment more difficult. The treatment for hyperthyroidism is not quite as easy, inexpensive or painless as that for hypothyroidism. If your are hyperthyroid, your doctor may attempt to shrink your thyroid with radioactive iodine. In this procedure, radioactive iodine is used to destroy the cells that produce thyroid hormone, thus lessening the amount of thyroid hormone produced. Although this procedure is effective in treating hyperthyroidism, its usual end result is to render you hypothyroid. That means you -- like people who are hypothyroid because of Hashimoto's disease or surgery for thyroid cancer -- must take synthetic thyroid hormone to replace the hormone your thyroid no longer makes in sufficient quantities. Antithyroid (thyroid blocking) drugs are less frequently used to stop your thyroid from producing excess hormone. If drug therapy fails, radioactive iodine is used. Remember to see your doctor for checkups... Once you have been prescribed thyroid hormone replacement therapy, it is important to continue seeing your doctor for checkups. Your physician may obtain thyroid function tests annually and, depending on the results, adjust your dose of thyroid hormone. Moreover, during pregnancy, and as you grow older, your thyroid hormone requirements change, which may necessitate a dosage adjustment. In the past, physicians used to prescribe higher doses of thyroid hormone. Now accurate tests are available to determine precisely how much hormone a person needs, physicians can prescribe smaller, equally effective doses. If you have been taking levothyroxine or any other thyroid medicine for many years and have not been checked recently, you may want to ask your physician whether it is time to review your dosage needs. A word about thyroid hormone preparations... All thyroid hormone preparations are not the same. If your physician prescribes a certain brand of levothyroxine and your pharmacist asks if you would like to switch from that brand, please check with your physician first. Even though the labels say that the two preparations have the same strength, they may not deliver exactly the same amount of thyroid hormone. A leading consumer magazine and most U.S. endocrinologists agree: Thyroid medications should only be switched in conjunction with complete retesting. Desiccated thyroid. Many older people with hypothyroidism have been taking a different kind of thyroid medication call desiccated thyroid, which was prescribed in the years before synthetic levothyroxine became available. Desiccated thyroid tablets are made from animal thyroid glands and contain a form of thyroid hormone that can cause a rapid heartbeat and other undesirable effects on the heart. Most experts today consider desiccated thyroid an outmoded medication. If you were diagnosed as having hypothyroidism 20 to 30 years ago...and if you've been on the same medication ever since...you should check with your doctor. Anyone taking desiccated thyroid--often called "thyroid extract" or "thyroid pills"--should contact a physician to determine whether he or she should be taking levothyroxine instead. If you would like more information about thyroid disease, you may want to contact: Thyroid Foundation of America, Inc. 630 Ambulatory Care Center Massachusetts General Hospital Boston, Massachusetts 02114