Thyroid Nodules

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 thyroid gland, which is made up of a right lobe and a left lobe, produces and secretes thyroid hormones into the bloodstream. Thyroid hormones are important to functions that include regulating the metabolic rate and body temperature, and helping to maintain heart functioning.

What causes a thyroid nodule to form?

Sometimes normal tissue begins to grow causing one or more nodules to form. The most important cause related to the development of thyroid nodules is thyroid cancer, but this, fortunately, is a very rare cause (about 5%). Other causes can include an iodine deficiency, suppression of thyroid hormone, and Hashimoto's disease (a chronic inflammation of the thyroid gland).

Most thyroid nodules are benign (noncancerous). The different types of thyroid nodules are defined as follows:

• Colloid nodules. These are one or more overgrowths of normal thyroid tissue. These growths are noncancerous, may grow large, but do not spread beyond the thyroid gland.
• Thyroid cysts. These are fluid-filled or partially fluid-filed, partially solid growths within the thyroid gland.
• Inflammatory nodules. These develop as a result of chronic inflammation of the thyroid gland. These growths may or may not cause pain.
• Thyroid cancer. Nodules may be the result of cancer in less than 10 percent of cases.
• Multinodular goiter. One of the possible causes of goiter (an enlargement of the thyroid gland) is the presence of thyroid nodules.
• Hyperfunctioning thyroid nodules. These nodules produce thyroid hormone and may lead to the development of hyperthyroidism.

How do I know if I have thyroid nodules?

Most thyroid nodules do not produce any symptoms. However, large nodules or multiple nodules may 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 cause symptoms of hyperthyroidism, which include:

• Irritability/nervousness
• Muscle weakness/tremors
• Infrequent, scant menstrual periods
• Weight loss
• Sleep disturbances
• Enlarged thyroid gland
• Vision problems or eye irritation
• Heat sensitivity
• Increased appetite
• Clammy skin
• Skin blushing
• Bounding pulse

Thyroid nodules that result from Hashimoto's disease may cause symptoms of hypothyroidism, including:

• Fatigue
• Frequent, heavy menstrual periods
• Forgetfulness
• Weight gain
• Dry, coarse skin and hair
• Hoarse voice
• Intolerance to cold

Are there factors that increase my risk of getting thyroid nodules?

The following factors are known to increase your risk:

• Family history. Having parents or siblings who have had thyroid nodules or thyroid or other endocrine cancers increases your chance of developing nodules.
• Age. The chance of developing nodules increases with increasing age.
• Gender. Women are more likely to develop thyroid nodules then men.
• Radiation exposure. A history of radiation exposure to the head and neck (from medical treatments) increases your risk of developing nodules.

The risk factors for a cancerous nodule include the risk factors mentioned above, except female gender, plus:

• Having a nodule that is hard
• Having a nodule that is stuck to nearby structures
• Being of male gender
• Age younger than 20 and older than 70

How are thyroid nodules diagnosed?

Sometimes you can feel the nodule yourself or your doctor may discover it during an exam. More often your doctor will need to order one or more of the following tests:

• Thyroid hormone level test. This is a blood test that checks the levels of hormones secreted by the thyroid gland. Most often, the hormone levels are normal despite the presence of nodules (abnormal levels are sometimes associated with noncancerous nodules), so your doctor will likely need to order other tests listed below.
• Fine-needle biopsy of the thyroid gland. With this test, done in your 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 for analysis. Most nodules diagnosed using this method turn out to be noncancerous. If the analysis turns out to be "suspicious," your doctor may repeat this test or may refer you for surgery to have the nodules removed to make a definitive diagnosis.
• Thyroid ultrasound. This test uses sound waves to determine if a nodule is solid or a fluid-filled cyst. This test also can monitor the growth of nodules and is helpful if nodules are difficult to feel. In addition, thyroid ultrasound is sometimes used to help guide needle placement during a fine needle biopsy.
• Thyroid scan. With 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 assisting in determining if the nodules are cancerous or noncancerous.

How are thyroid nodules treated?

Treatment depends on the type of thyroid nodule you have. Treatment options include:

• No treatment. If you have a noncancerous nodules, you and your doctor may simply choose to monitor your condition through timely check-ups.
• Thyroid hormone suppression therapy. Some doctors treat noncancerous nodules with levothyroxine, a synthetic form of the thyroid hormone thyroxine. The theory is that this drug signals the pituitary to produce less of another thyroid hormone responsible for thyroid tissue growth. The goal of this treatment is to shrink the nodules. Debate continues in the medical community whether the evidence consistently shows that this treatment actually works to shrink the 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.
• Alcohol ablation. The aim of this treatment, similar to radioactive iodine treatment, is to shrink thyroid nodules and decrease symptoms of hyperthyroidism. With this treatment, hyperfunctioning nodules are injected with ethyl alcohol (ethanol).
• 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).

Where can I learn more about thyroid nodules and other thyroid diseases?

Contact or review the web sites of the following organizations:

American Foundation of Thyroid Patients
P.O. Box 4914
Odessa, TX 79760
www.thyroidfoundation.org

American Thyroid Association
6066 Leesburg Pike, Suite 550
Falls Church, Virginia 22041
1.800.THYROID
www.thyroid.org

Thyroid Foundation of America, Inc.
One Longfellow Place, Suite 1518
Boston, MA 02114
1.800.832.8321
www.tsh.org

The Hormone Foundation
8401 Connecticut Avenue
Suite 900
Chevy Chase, MD 20815-5817
1.800.HORMONE
www.hormone.org

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.

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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: 8/10/2006