Thyroid Nodules

June 15, 2024 
This page was reviewed under our medical and editorial policy by Sasan Fazeli, M.D., assistant clinical professor in the Department of Diabetes, Endocrinology and Metabolism, and Karen Tsai, M.D., assistant clinical professor in the Department of Diabetes, Endocrinology and Metabolism, City of Hope^® Cancer Center Duarte.

A thyroid nodule (lump) may form when there is an overgrowth of cells in the thyroid gland.

What Is a Thyroid Nodule?

The thyroid is a butterfly-shaped gland found just below the Adam’s apple, at the base of the neck. It produces vital hormones that regulate heart rate, blood pressure, the process to turn food into energy (metabolism) and body temperature.

A thyroid nodule is a lump that develops from an overgrowth of cells in the thyroid gland. They are more common in women than in men. The chances of developing one increase as people grow older.

Nodules may be solid or filled with fluid. They may develop into one lump or several. Some nodules make thyroid hormones (hot nodules). Others do not (cold nodules).

More than 85% of these nodules are noncancerous (benign). Testing is recommended in high-risk nodules to detect thyroid cancer early so treatment may begin.

Thyroid Nodule Symptoms

Thyroid nodules often have no symptoms and are commonly discovered during a routine medical checkup or during tests, such as imaging, performed for other reasons.

Larger nodules may produce symptoms, such as:

• A lump on the front of the neck, caused by an enlarged thyroid (goiter)
• Difficulty breathing or swallowing
• A tickle or discomfort in the throat
• Neck pain
• Hoarseness or voice change

When the nodules produce excessive thyroid hormones, patients may have symptoms of an overactive thyroid, such as:

• Increased appetite
• Unintentional weight loss
• Warm, sweaty or flushed skin
• Rapid or irregular heartbeat
• Anxiety or nervousness
• Restlessness, trouble sleeping
• More frequent bowel movements
• Change in menstrual periods
• Trembling or shaky movements (tremors)

Diagnosing Thyroid Nodules

It’s important to distinguish benign (non-cancerous) thyroid nodules from thyroid cancer in order to recommend appropriate treatments and monitoring. Listed below are some of the tests doctors use to better characterize benign thyroid nodules from thyroid cancer.

Blood tests: Thyroid-stimulating hormone (TSH) and other thyroid hormone levels are measured using a sample of blood taken from the inner elbow or hand with a small hollow needle. These thyroid hormone lab tests help the physician better understand the patient’s thyroid hormone status.

Thyroid ultrasound: An ultrasound uses high-frequency sound waves to provide a clear picture of the thyroid. This test will show the doctor if nodules are fluid-filled (cystic) or solid. It will also show how many are present, their exact size and specific characteristics. Ultrasound is also used to guide needle placement when a biopsy is performed. It may also be used to monitor thyroid nodules serially to evaluate for changes in characteristics or size overtime.

Fine needle aspiration biopsy (FNAB, FNB or FNB): After numbing the skin (local anesthetic), the doctor will insert a small needle through the skin and into the nodule, using the ultrasound images as a guide. Several tissue samples are usually taken and sent to the laboratory to be examined under a microscope. additional tissue samples may be sent for molecular testing. This simple test requires no special preparation other than asking patients who take blood thinners to stop using them for a few days beforehand. The procedure is often performed in the doctor’s office, and many patients return to work immediately afterward without any activity limitations.

Thyroid scan: This test, which examines the thyroid’s structure and function, is less common. It may be ordered if the patient’s TSH level is low, suggestive of high thyroid levels in the body (a condition called hyperthyroidism). A small dose of radioiodine is given in pill form. Four to six hours later, initial pictures are taken once the radioiodine has collected in the thyroid, and pictures are taken again 24 hours later. During the test, the patient has to lie still on a moveable table while the machine takes pictures of the thyroid. Patients may have to fast before the test, may need to have certain medications held beforehand (such as methimazole or propylthiouracil) or follow a low-iodine diet days prior to the exam. Nodules that absorb the radioiodine, called hot nodules, are less likely to be cancerous. Nodules that do not absorb radioiodine, called cold nodules, have a higher likelihood of being cancerous.

Molecular diagnostics: These highly specialized tests examine tissue from thyroid nodule biopsy samples. Molecular testing looks for specific genetic changes, which may help the physician determine whether the thyroid nodule is cancerous or non-cancerous (benign).

Thyroid Nodule Causes

Although the cause of a thyroid nodule is not always known, it is sometimes linked to Hashimoto’s disease, in which the immune system attacks the thyroid gland. People who have had radiation therapy treatment close to the thyroid have a higher risk of developing nodules. Nodules have also been linked to iodine deficiency, which is rare in the United States.

Types of Thyroid Nodules

Thyroid nodules occur in different form, as:

• Solid or containing fluid (cyst)
• Nodules that produce thyroid hormone (hot) and those that do not (cold)
• Benign (noncancerous), thyroid cancer or, infrequently, a different cancer (such as lymphoma or metastasis of another cancer)
• A single nodule or multiple nodules

Calcified Thyroid Nodule

Calcified thyroid nodules are hard due to a buildup of calcium or other minerals. They may develop with aging, inflammation or injury. Calcifications that occur as large, coarse flecks (macrocalcification) are usually benign. Microcalcifications are more worrisome for thyroid cancer.

Colloid Thyroid Cyst

A colloid thyroid nodule is caused by an overgrowth of thyroid tissue. When it is partially or completely filled with fluid, it is called a colloid thyroid cyst. Cysts that only contain fluid are considered benign.

Hyperfunctioning Thyroid Nodules

A hyperfunctioning or “hot” thyroid nodule refers to an area on the thyroid gland that makes too much thyroid hormone. On radioactive examination, the radioiodine tracer concentrates in this nodule area and is visible on the radioactive iodine scan as a brighter (hot) spot. Follicular adenomas are an example of these nodules. This type of nodule is typically benign, and treatment focuses on correcting thyroid hormone levels with radiofrequency ablation of the nodule (RFA), surgery, anti-thyroid medication or radioactive iodine ablation treatment.

Multinodular Goiter

A multinodular goiter (MNG) is common and happens when several areas within the thyroid gland enlarge. It may also be called an adenomatous goiter, a nontoxic nodular goiter or a colloid nodular goiter. After several years, if some of the nodules start producing thyroid hormone, it becomes a toxic multinodular goiter (explained below).

Thyroid Cysts

Thyroid cysts are nodules that contain fluid. Some only contain fluid (simple), while others have fluid and other substances (complex). Simple cysts are usually benign.

While the cyst collapses when fluid is removed, it may come back. Treatment in large thyroid cysts may include removing the fluid (aspiration) and injecting ethanol solution (ethanol ablation), or surgery.

Toxic Nodular Goiter

Toxic nodular goiters are enlarged (swollen) thyroid glands. One or more areas within the thyroid form a nodule and produce too much thyroid hormone. Toxic multinodular goiter (MNG) is also called Plummer disease.

Some treatments — explained in more detail below — may include surgery to remove all or part of the thyroid, radiofrequency ablation (RFA) of the toxic nodules, radioactive iodine therapy or anti-thyroid medications.

Thyroid Nodule Treatment

Thyroid nodule treatment choices depend on the type of nodule, whether it is producing too much thyroid hormone and whether it is causing compressive issues with breathing, swallowing or changes in the voice.

Treatment options may include those listed below.

Observation and monitoring: If the nodules are noncancerous (benign), such as colloid, goiter or Hashimoto’s thyroiditis, no surgical treatment is advised. Patients are typically followed closely with ultrasounds every six to 24 months, as well as a yearly physical exam with bloodwork.

Surgery: Large benign nodules may be removed surgically if they are causing difficulties with breathing or swallowing. Part of the thyroid (lobectomy) or all of it (thyroidectomy) may be removed.

Radiofrequency thyroid nodule ablation: A needle-like probe is inserted into the nodule using ultrasound for guidance. Heat is passed through the probe to destroy the nodule from inside and shrink it. RFA is most effective in solid or mostly solid thyroid nodules.

Radioactive iodine (RAI) therapy: Radioactive iodine is usually given in capsule form. It collects in the thyroid, where the radiation destroys the thyroid tissues.

Ethanol ablation: An ethanol solution is injected into the thyroid cyst, causing the cyst to shrink. Ethanol ablation is most effective in thyroid cysts (fluid-filled nodules).

Medication: Thyroid medication may be given to treat low thyroid levels (hypothyroid). Anti-thyroid medication may be given to suppress an over-functioning thyroid (hyperthyroid).

When to Worry About Thyroid Nodules

If a thyroid nodule suddenly appears, is growing, causes symptoms, or occurs in someone with a family history of thyroid cancer, it’s a good idea to have it evaluated by a doctor right away.

In most cases, small, noncancerous thyroid nodules are monitored with imaging and don’t require additional treatment. If some or all of the thyroid gland is removed, medications are given to maintain thyroid hormone levels.

If the nodule is cancer, it is typically very treatable. If a lump is concerning, it’s important to have a doctor look at it.