The thyroid is the largest gland in the neck. Its shape resembles that of a butterfly, with its wings wrapping around the trachea. Its function is to make the thyroid hormone. This particular hormone impacts almost every tissue in the body, but its overall function is to regulate the body's metabolism. Common disorders include hyperthyroidism (metabolism too fast), hypothyroidism (metabolism too slow) and thyroid nodules. Treatment for these conditions may include selective destruction of overactive thyroid tissue, hormone replacement, or identification of the type of thyroid nodule involved followed by a possible surgical intervention or periodic monitoring.