Management of Patients With Thyroid Disorders
The thyroid gland is a butterfly-shaped organ located in the lower neck anterior to the trachea (Fig. 42-3). It consists of two lateral lobes connected by an isthmus. The gland is about 5 cm long and 3 cm wide and weighs about 30 g. The blood flow to the thyroid is very high (about 5 mL/min per gram of thyroid tissue), about five times the blood flow to the liver. This reflects the high meta-bolic activity of the thyroid gland. The thyroid gland produces three hormones: thyroxine (T4), triiodothyronine (T3), and cal-citonin. Thyroxine and triiodothyronine are referred to collec-tively as thyroid hormone.