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Thyroid nodule

Definition

A thyroid nodule is a growth (lump) in the thyroid gland. The thyroid gland is located at the base of the neck.

Alternative Names

Thyroid tumor; Thyroid adenoma; Thyroid carcinoma; Thyroid incidentaloma

Causes, incidence, and risk factors

Thyroid nodules are growths of cells in the thyroid gland. These growths can be noncancerous (benign) or cancerous (malignant). Some nodules are fluid-filled (cysts), while others are made of thyroid gland cells. Sometimes, what feels like one nodule will actually be a collection of small nodules.

Thyroid nodules are more common in women than in men. A person's chance of a thyroid nodule increases with age.

Only a few thyroid nodules are cancerous. (See: Thyroid cancer)

The following characteristics increase the chances that a thyroid nodule is cancerous:

• A hard nodule
• A nodule that is stuck to nearby structures
• Family history of multiple endocrine neoplasia type II
• Family history of thyroid cancer, especially medullary thyroid carcinoma
• Hoarse voice due to vocal cord paralysis
• Age -- younger than 20 years or older than 70
• History of radiation exposure to the head or neck
• Male gender

Causes of thyroid nodules are not always found, but can include:

• Hashimoto's disease
• Iodine deficiency

Symptoms

Most thyroid nodules produce no symptoms.

Large nodules can press against other structures in the neck. Symptoms may include:

• Difficulty breathing
• Difficulty swallowing
• Goiter
• Hoarseness or changing voice
• Pain in the neck

Nodules that produce thyroid hormones will cause symptoms of hyperthyroidism, including:

• Bounding pulse
• Clammy skin
• Increased appetite
• Nervousness
• Restlessness
• Skin blushing or flushing
• Weight loss

Thyroid nodules are sometimes found in people who have Hashimoto's disease. Hashimoto's disease may cause hypothyroidism, with symptoms such as:

• Dry skin
• Facial swelling
• Fatigue
• Hair loss
• Intolerance to cold
• Unintentional weight gain

Signs and tests

Very often, nodules produce no symptoms. Doctors will find thyroid nodules only during a routine physical exam or imaging tests that are done for another reason. However, thyroid nodules that are big enough to feel during a physical exam occur in a few people.

If the doctor finds a nodule or you have symptoms of a nodule, the following tests may be done:

• Fine needle aspiration biopsy
• Thyroid scan
• Thyroid ultrasound
• TSH level

Treatment

Your health care provider may recommend surgery to remove all or part of your thyroid gland if the nodule is:

• Cancerous
• Believed to be making your thyroid overactive (hyperthyroid)
• Cannot be diagnosed as cancer or noncancer
• Cause symptoms such as swallowing or breathing problems

Patients with overactive nodules may be treated with radioactive iodine, which reduces the size and activity of the nodule. However, in rare cases the treatment can cause hypothyroidism and inflammation of the thyroid gland (radiation-induced thyroiditis). Pregnant women should not be given this treatment. Women being treated with radioactive iodine should not get pregnant.

Levothyroxine (thyroid hormone) is a drug that suppresses the production of the thyroid hormone T4. A doctor may prescribe levothyroxine to treat noncancerous nodules only in special cases.

Careful follow-up is the only recommended treatment for benign nodules that do not cause symptoms and are not growing. A thyroid biopsy may need to be repeated 6 - 12 months after diagnosis. An ultrasound may be repeated as well.

Other possible treatments include ethanol (alcohol) injection into the nodule and laser therapy.

Expectations (prognosis)

Noncancerous thyroid nodules are not life threatening. Many do not require treatment, only follow-up. Noncancerous nodules that do need treatment have an excellent outlook.

The outlook for cancerous nodules depends on the type of cancer.

See also: Thyroid cancer

Complications

Hyperthyroidism is a common complication of noncancerous thyroid nodules.

Complications of treatment can include:

• Hoarse voice if vocal cord nerves are damaged during surgery
• Hypothyroidism from surgery or radioactive iodine therapy
• Low blood calcium (hypocalcemia) from hypoparathyroidism if parathyroid glands are accidentally damaged or removed during surgery

Calling your health care provider

Call your health care provider if you feel or see a lump in your neck, or if you experience any symptoms of a thyroid nodule.

If you have been exposed to radiation in the face or neck area, call your health care provider. A neck ultrasound can be done to look for thyroid nodules.

Prevention

The reason for most thyroid nodules is unknown. A diet with enough iodine will help prevent some nodules.

References

Gharib H, Papini E, Valcavi R, et al.; AACE/AME Task Force on Thyroid Nodules. American Association of Clinical Endocrinologists and Associazione Medici Endocrinologi medical guidelines for clinical practice for the diagnosis and management of thyroid nodules. Endocr Pract. 2006;12:63-102.

Schlumberger MJ, Filetti S, Hay ID. Nontoxic Diffuse and Nodular Goiter and Thyroid Neoplasia. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 13.