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Hyperthyroidism - Overview

Alternative Names

Thyrotoxicosis; Overactive thyroid

Definition of Hyperthyroidism:

Hyperthyroidism is a condition in which the thyroid gland is overactive, and makes too much thyroid hormone (called thyroxine [T4 ] and triiodothyronine [T3 ]). Hormones are substances that affect and control many important functions in the body.

Causes, incidence, and risk factors:

The thyroid gland is located in the neck. It produces several hormones that control the way every cell in the body uses energy (metabolism). The thyroid is part of the endocrine system.

Hyperthyroidism occurs when the thyroid releases too much of its hormones over a short (acute) or long (chronic) period of time. Many diseases and conditions can cause this problem, including:

Getting too much iodine
Graves disease
Inflammation (irritation and swelling) of the thyroid due to viral infections or other causes
Non-cancerous growths of the thyroid gland or pituitary gland
Taking large amounts of thyroid hormone
Tumors of the testes or ovaries

Graves disease accounts for 85% of all cases of hyperthyroidism.

References

AACE Thyroid Task Force. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism. Endocr Pract. 2002;8(6).

Davies TF, Larsen PR. Thyrotoxicosis. In: Koronenberg HM, Shlomo M, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 11.

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