Health Conditions

What is it?

Hyperthyroidism is a medical condition caused by the effects of too much thyroid hormone on tissues of the body. Although there are several different causes of hyperthyroidism, most of the symptoms that patients experience are the same regardless of the cause (see the list of symptoms below). Because the body's metabolism is increased, patients often feel hotter than those around them and can slowly lose weight even though they may be eating more. Sometimes patients actually gain weight because of an increase in their appetite. Patients with hyperthyroidism usually experience fatigue at the end of the day, but have trouble sleeping. Trembling of the hands and a hard or irregular heartbeat (called palpitations) may develop. These individuals may become irritable and easily upset. When hyperthyroidism is severe, patients can suffer shortness of breath, chest pain, and muscle weakness. Symptoms can continue for weeks or months before patients fully realize that they are sick.

So what is the thyroid gland and why is thyroid hormone important? The thyroid gland is a small, butterfly-shaped gland located in the neck just under the Adam's apple. The thyroid gland produces thyroid hormone, which acts on many different parts of the body including the muscles, brain, heart, intestines, and skin and helps regulate many bodily functions such as water balance, fat and sugar metabolism, and body temperature. The thyroid gland and its release of thyroid hormone are actually controlled by other glands in the body, the pituitary and hypothalamus. The hypothalamus senses the level of thyroid hormone in the blood and releases a hormone called thyrotropin releasing hormone (TRH). TRH stimulates the pituitary to release thyroid stimulating hormone (TSH) which then acts on the thyroid to secrete thyroid hormones.

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