What are thyroid nodules?
A thyroid nodule is an abnormal growth (lump) of thyroid cells within the thyroid gland.
The thyroid is a hormone-producing, butterfly-shaped organ (or gland) that is located on the front of the neck, just under the Adam's apple (the larynx). The thyroid gland, which is made up of a right lobe and a left lobe, produces and secretes thyroid hormones into the bloodstream. Thyroid hormones govern functions such as body temperature, digestive and heart functions, and all body processes needed for life.
What causes a thyroid nodule to form?
Sometimes thyroid tissue begins to grow, causing one or more nodules to form. The reason why this happens is unknown. Cancer (malignancy) is the biggest concern when nodules form. Fortunately, cancer is very rare – found in less than 5 percent of all nodules. Nodules develop more often in those with a family history of nodules and in individuals with iodine deficiency. Iodine is needed to make thyroid hormone.
There are different types of thyroid nodules.
- Colloid nodules. These are one or more overgrowths of normal thyroid tissue. These growths are not cancerous (benign), may grow large, but do not spread beyond the thyroid gland.
- Thyroid cysts. These are fluid-filled or partially solid/partially fluid-filled growths inside the thyroid gland.
- Inflammatory nodules. These nodules develop as a result of chronic inflammation of the thyroid gland. These growths may or may not cause pain.
- Multinodular goiter. Sometimes an enlarged thyroid (goiter) is composed of many, usually benign, nodules.
- Hyperfunctioning thyroid nodules. These nodules produce thyroid hormone, which may lead to the development of hyperthyroidism. Hyperthyroidism can affect the heart, leading to such complication as sudden cardiac arrest, hypertension, arrhythmias; as well as osteoporosis and other health problems.
- Thyroid cancer. Of the nodules that can form as the thyroid gland enlarges, fortunately, less than 5 percent are cancerous.
How do I know if I have thyroid nodules?
Most thyroid nodules do not produce any symptoms. However, large nodules or multiple nodules may be visible. Although rare, nodules can press against other structures in the neck and cause symptoms including:
- Difficulty swallowing
- Difficulty breathing
- Hoarseness or voice change
- Pain in neck
- Goiter (enlargement of the thyroid gland)
Hyperfunctioning thyroid nodules will sometimes, but not always, cause symptoms of hyperthyroidism. Hyperthyroidism results from an overproduction of thyroid hormone. This causes the levels of thyroid hormone in the blood to be too high. Symptoms of hyperthyroidism include:
- Muscle weakness/tremors
- Light or missed menstrual periods
- Weight loss
- Difficulty sleeping
- Enlarged thyroid gland
- Vision problems or eye irritation
- Heat sensitivity
- Increase or decrease in appetite
- Shortness of breath
- Itchy skin/clammy skin
- Thinning hair
- Skin flushing (sudden reddening of face, neck or upper chest)
- Heart palpitations
Thyroid nodules sometimes result from Hashimoto's disease and may be associated with symptoms of hypothyroidism. Hypothyroidism is a condition that results from an underactive thyroid gland. This causes the levels of thyroid hormone in the blood to be too low. Symptoms of hypothyroidism include:
- Frequent, heavy menstrual periods
- Weight gain
- Dry, coarse skin and hair; hair loss
- Hoarse voice
- Cold intolerance
Are there factors that increase my risk of getting thyroid nodules?
Risk factors for developing thyroid nodules include:
- Family history. Having parents or siblings who have had thyroid nodules or thyroid or other endocrine cancers increases your chance of developing nodules. The endocrine system is made up of glands that secrete various hormones into the bloodstream. These hormones manage all the bodily functions necessary for life.
- Age. The chance of developing nodules increases with age
- Gender. Women are more likely than men to develop thyroid nodules.
- Radiation exposure. A history of radiation exposure to the head and neck (from medical treatments but not from diagnostic procedures -- such as a CT scan) increases your risk of developing nodules.
Risk factors for developing cancerous thyroid nodules include:
- Family history of nodules
- Having a nodule that is hard
- Having a nodule that is stuck to nearby structures
- Male gender
- Age younger than 20 and older than 70
- Radiation exposure
How are thyroid nodules diagnosed?
Sometimes you can feel the nodule yourself or your doctor may discover it during an exam. However, your doctor will usually need to order one or more of the following tests:
- Thyroid hormone level test. This blood test checks the levels of hormones secreted by the thyroid gland. Most often, the hormone levels are normal despite the presence of nodules. However, there are times when abnormal hormone levels are also benign. Therefore your doctor will likely order other tests.
- Fine-needle biopsy of the thyroid gland. With this test, done in the doctor's office, a very thin needle is used to withdraw a sample of cells from one or more thyroid nodules. The samples are then sent to a laboratory. Most nodules diagnosed using this method turn out to be noncancerous. However, if the test results to be "suspicious," your doctor may repeat this test or may refer you for surgery to have the nodules removed to make an accurate diagnosis.
- Thyroid ultrasound. This test uses sound waves to determine if a nodule is solid or a fluid-filled cyst. (The risk of cancer is higher in solid nodules.)This test also monitors the growth of nodules and it helps find nodules that are difficult to feel. In addition, thyroid ultrasound is sometimes used to help guide needle placement during a fine needle biopsy.
- Thyroid scan. In this test, a small amount of radioactive iodine is injected into a vein. The degree to which the radioactive iodine is absorbed by the nodules compared with normal thyroid tissue helps determine if the nodules are benign or malignant. This test is ordered infrequently since it is only useful in certain circumstances.
How are thyroid nodules treated?
Treatment depends on the type of thyroid nodule. Treatment options include:
- No treatment/"watchful waiting." If the nodules are not cancerous, you and your doctor may decide that no treatment is needed at this time. The nodules will be closely watched for any changes through frequent check-ups.
- Thyroid hormone suppression therapy. Some doctors treat noncancerous nodules with levothyroxine, a synthetic form of the thyroid hormone thyroxine. The medical theory is that this drug signals the pituitary to produce less of another thyroid hormone responsible for thyroid tissue growth. (The pituitary is a small gland in the brain that controls the thyroid gland.) The goal of levothyroxine treatment is to shrink the thyroid nodules. Doctors and researchers are still studying if this treatment actually works to shrink nodules.
- Radioactive iodine. Your doctor may use radioactive iodine to treat hyperfunctioning thyroid nodules and multinodular goiters. The radioactive iodine is absorbed into the thyroid gland, causing the nodules to shrink. Pregnant women and women trying to become pregnant should not undergo this treatment.
- Surgery. Surgery to remove nodules is the best treatment for nodules that are cancerous, that cause symptoms (eg, are so large that they make breathing or swallowing difficult), and that are "suspicious" (ie, cannot be diagnosed as cancerous or noncancerous without being surgically removed and examined).
Thyroid Nodule Fast Facts
- Thyroid nodules are very common. They occur in about 4 percent of women.
- About 95 percent of thyroid nodules are benign
- Thyroid screening is a simple exam of the neck done by a health care professional to detect enlargement of the thyroid (goiter) or thyroid nodules. This exam is recommended for people who have a family history of thyroid disease or previous history of radiation to the face or neck.
- American Thyroid Association. Thyroid Nodules. www.thyroid.org/ Accessed 1/6/2012
- National Institutes of Health. National Institute of Diabetes and Digestive and Kidney Diseases. National Endocrine and Metabolic Diseases Information Service. Hyperthyroidism. www.endocrine.niddk.nih.gov/ Accessed 1/6/2012
- The Hormone Foundation. www.hormone.org/ Accessed 1/6/2012.
© Copyright 1995-2012 The Cleveland Clinic Foundation. All rights reserved
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 1/6/2012...#13121