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 adenoma; Thyroid carcinoma; Thyroid incidentaloma

Causes, incidence, and risk factors:

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

Thyroid nodules that are big enough to feel during a physical exam occur in 5 - 7% of the population. Smaller nodules occur in as many as 50% of people aged 60 or older. Thyroid nodules are more common in women than in men. A person's chance of a thyroid nodule increases with age.

Only 4 - 5% of thyroid nodules are cancerous. (See: Thyroid cancer )

The following characteristics increase the risk for a cancerous nodule:

Family history of medullary thyroid carcinoma
Family history of multiple endocrine neoplasia Type II
A hard nodule
A nodule that is stuck to nearby structures
Vocal cord paralysis

Other risk factors for a cancerous nodule include:

Male gender
Age -- younger than 20 years or older than 70
History of radiation exposure to the head or neck

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

Iodine deficiency
Suppression of thyroid hormone
Hashimoto's disease

References:

Sriram U, Patacsil LM. Thyroid Nodule. Dis Mon 2004; 50(9):486-526.

Hegedus L. The Thyroid Nodule. N Eng J Med 2004;351:1764-71.

Goldman L, Ausiello D. Cecil Textbook of Medicine , 22nd ed. Philadelphia, Pa: WB Saunders; 2004.

Rakel RE. Textbook of Family Practice . 6th ed. Philadelphia, Pa: WB Saunders; 2005.

Review Date: 5/11/2006
Reviewed By: Rita Nanda, MD, Department of Medicine, Section of Hematology/Oncology, University of Chicago Medical Center, Chicago, IL. Review provided by VeriMed Healthcare Network.

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