What is a thyroid nodule?
A nodule is a small lump, or localized growth in part of the thyroid gland. It differs from a goiter, which is an enlarged thyroid gland. However, an enlarged thyroid gland (goiter) may contain one or more nodules. A nodule is an area of the gland that appears to be different than the rest by being raised or a different texture. Nodules are very, very common. In most cases they are not cancerous, but a physician should evaluate them all. These growths may be fluid filled (cysts) or solid and formed of thyroid tissue. They may be mixtures of solid and cysts and can bleed into themselves and appear to enlarge in a matter of hours. Nodules can be very small, less than a millimeter, or as large as a few inches. They can occur alone or with others of different sizes in the same gland. Nodules are not a disease, but are a sign of an underlying problem in the thyroid gland. The cause of the nodules needs to be determined.
What causes a nodule?
Between 90-95% of all nodules are benign, noncancerous overgrowths of thyroid tissue. Only about 5% are cancerous. Because of the chance of a nodule being cancerous, all nodules should be fully evaluated. The causes of the benign nodules include a cyst (collection of fluid), thyroid tissue that is overactive (hyperactive nodule), or many growths in an enlarged thyroid gland (multinodular goiter).
What are the symptoms of a thyroid nodule?
Most often they have no symptoms, but can press against the neck and cause a sensation of a lump in the throat, difficulty swallowing, hoarseness or a cough. A nodule can produce excess thyroid hormone (hyperactive nodule) and symptoms of hyperthyroidism - fast heart rate, weight loss, feeling jittery or nervous, diarrhea, tremor. Nodules are sometimes found in a thyroid gland that is underactive, a condition known as hypothyroidism. Symptoms of hypothyroidism include slow heart rate, weight gain, constipation's, depression and fatigue.
How common are nodules in the thyroid?
In a word - very. It is estimated that about 50% of the population will develop a small, unnoticeable thyroid nodule at some time in their life. Most nodules are never detected and do not cause problems. In fact they are only found by doing an ultrasound, a specialized x-ray of the gland. Only 4-7% of the population will have a nodule that is large enough to be found by a physician feeling, or palpating, for it. They are more common in women and the incidence of nodules increases with age. About 4% of women aged 20 years have a palpable nodule whereas 9% of women over age 70 have a palpable nodule. Nodules are only found in about 1% of men.
How do I tell if I have a nodule?
You can check your own thyroid by standing in front of a mirror. Look at the area of your neck just above the notch where the collarbone comes together and just below the adam's apple. This is where the thyroid gland is located. If possible, have a light shine from the side to throw a shadow over the area. Then tilt your head back slightly and watch this area for any shadows while you swallow. If you see any prominence or enlargement in this area, you may have a thyroid nodule or an enlarged thyroid gland (goiter). See your physician for a more complete check up. You should also have your thyroid gland area examined during a general physical examination by a medical care provider.
What should I do if I have a nodule?
If you have a nodule, you should have it evaluated by a physician trained in the diagnosis and management of thyroid nodules. Endocrinologists, internal medicine specialists, ear, nose and throat specialists, and endocrine surgeons are experienced in assessing nodules. The doctor will take a careful history for risk factors for thyroid disease (including radiation exposure), do a physical examination and order blood tests to check the activity of the gland. In most cases, the best approach is to have a small aspiration of the nodule done, a procedure called a fine needle aspirate (fna). An ultrasound test may be performed to accurately measure the nodule and check for others in the gland. A thyroid scan may also be recommended to see if the nodule is overactive (a "hot" nodule) or inactive (a "cold" nodule). These tests are not dangerous nor particularly painful. The most accurate test is the fine needle aspirate, which should be done with at least six samples from each nodule.
Does radiation cause nodules?
Certain forms of radiation have been associated with increased risk of cancerous nodules in the thyroid. The risk is small and you have to be exposed to very high amounts of radiation, not the amounts that occur with regular x-rays or sun exposure. Radiation at hiroshima, chernobyl, and nuclear weapons testing in the us in the 1940-1970s have all been associated with increased risk of thyroid nodules and cancer. Regular x-rays or dental x-rays are not a known risk factor. However, if you had radiation treatments to your head, neck, tonsils, or thymus, you may be at a slightly increased risk of thyroid cancer. If you are concerned that you had exposure, see your doctor for a check up for thyroid nodules.
How is a nodule treated?
The treatment of a nodule depends upon its cause. If the fine needle aspirate from your thyroid nodule shows benign, non cancerous cells, then the nodule may just be watched to make sure that it does not grow larger. You may also be advised to take thyroid hormone to suppress the activity of the gland so that it does not grow other nodules. If it grows larger, you may need another biopsy. If the biopsy is inconclusive or indeterminate, it will be repeated. If the second biopsy comes back indeterminate, then you may be advised to have it removed surgically. This was the case with the vice-president's wife, tipper gore. She had two thyroid biopsies that were indeterminate and then she had part of her thyroid removed. Like most people, her nodule was not cancerous. If the fine needle biopsy is suspicious for cancer, then surgical removal is recommended. If you are advised to have surgery, then make sure that your surgeon is very experienced with thyroid gland surgery and has done at least 50 surgeries a year.
What if my nodule is cancer?
In the rare case that your nodule is cancerous, most often it is curable. Surgery is the main way to remove the cancerous nodule. Afterwards, you will take thyroid hormone tablets to replace the hormones made by your removed thyroid and to suppress the cancer cells' growth in any remaining thyroid tissue. You will be followed closely afterward, preferably with ultrasensitive tsh testing, and may be treated with radioactive iodine to destroy any remaining thyroid tissue so that it does not develop cancer. Some forms of thyroid cancer run in families, so if this type is identified, then you may be advised to have other family members checked.
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