hormonal and metabolic disorders
Hyperthyroidism
Introduction
Hyperthyroidism is overactivity of the thyroid gland that leads to high levels of thyroid hormones and speeding up of vital body functions. Graves disease is the most common cause of hyperthyroidism. Heart rate and blood pressure may increase, heart rhythms may be abnormal, and people may sweat excessively, feel nervous and anxious, have difficulty sleeping, lose weight without trying, and have an increased frequency of bowel movements. Blood tests can confirm the diagnosis. Usually,methimazoleorpropylthiouracilcan control hyperthyroidism. The thyroid gland secretes thyroid hormones, which control the speed at which the body’s chemical functions proceed (metabolic rate). Thyroid hormones affect many vital body functions, such as the heart rate, the rate at which calories are burned, skin maintenance, growth, heat production, fertility, and digestion. There are two thyroid hormones: T4: Thyroxine (also called tetraiodothyronine) T3:Triiodothyronine The pituitary gland produces thyroid-stimulating hormone (TSH), which stimulates the thyroid gland to produce thyroid hormones. The pituitary gland slows or speeds the release of TSH, depending on whether the levels of thyroid hormones circulating in the blood are getting too high or too low. (See also Overview of the Thyroid Gland .) Hyperthyroidism affects about 1% of people in the United States. It can occur at any age but is more common in women between the ages of 20 and 50 years. 