Hyperthyroidism causes
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Hyperthyroidism Microchapters |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Causes
Hyperthyroidism is the result of excess thyroid hormone production, causing an overactive metabolism and increased speed of all the body's processes.
Thyroid hormone generally controls the pace of all of the processes in the body. This pace is called one's metabolism. If there is too much thyroid hormone, every function of the body tends to speed up. The thyroid gland regulates the body temperature by secreting two hormones that control how quickly the body burns calories and energy. If the thyroid produces too much hormone, the condition is called hyperthyroidism, but if too little is produced, the result is hypothyroidism.
Major causes in humans are:
- Graves' disease (the most common etiology with 70-80%)
- Toxic thyroid adenoma
- Toxic multinodular goitre
Other causes of hyperthyroxinemia (high blood levels of thyroid hormones) are not to be confused with true hyperthyroidism and include subacute and other forms of thyroiditis (inflammation) and struma ovarii (a teratoma). Thyrotoxicosis (symptoms caused by hyperthyroxinemia) can occur in both hyperthyroidism and thyroiditis. When it causes acutely increased metabolism, it is sometimes called "thyroid storm", a life-threatening event characterized by tachycardia, hypertension, and fever.
Excess thyroid hormone from pills can also cause hyperthyroidism. Amiodarone, a heart medication, can sometimes cause hyperthyroidism. Hamburger toxicosis is a condition that occurs sporadically and is associated with ground beef contaminated with thyroid hormone.
Postpartum thyroiditis occurs in about 7% of women during the year after they give birth. PPT typically has several phases, the first of which is hyperthyroidism. Many times, the hyperthyroidism corrects itself within weeks or months without any treatment necessary.