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Thyroid nodule - Overview

Alternative Names

Thyroid tumor; Thyroid adenoma; Thyroid carcinoma; Thyroid incidentaloma

Definition of Thyroid nodule:

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

Causes, incidence, and risk factors:

Thyroid nodules are growths of cells in the thyroid glands. These growths can be non-cancerous (benign) or cancerous (malignant). 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:

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

Other risk factors for a cancerous nodule include:

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
Suppression of thyroid hormone

Reviewed last on: 6/17/2008
Elizabeth H. Holt, MD, PhD, Assistant Professor of Medicine, Section of Endocrinology and Metabolism, Yale University. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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.

Ladenson P, Kim M. Thyroid. In: Goldman L and Ausiello D, eds. Goldman: Cecil Medicine. 23rd ed. Philadelphia, Pa:Saunders; 2007:chap 244.

AACE/AME. 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.

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