The thyroid is a butterfly-shaped gland located in the neck, just above the clavicle. It is one of the endocrine glands that produce hormones. Thyroid hormones control the rhythm of many body activities. These include the speed with which calories are burned and how fast the heart beats. All these activities make up the body’s metabolism. For the diagnosis of thyroid diseases, doctors use patients’ medical history, a physical examination and tests for the thyroid. Sometimes they also use a biopsy. Treatment depends on the ailment but, it may include medications, radioactive iodine therapy, or thyroid surgery.