Hyperthyroidism or Graves disease (excessive production of thyroid hormones) usually results in elevated metabolism and activity. The treatment is to take an antithyroid drug. Hypothyroidism (deficiency of thyroid hormones) is usually characterized by lethargy and lowering of metabolism. This disease may result from disorders of the pituitary or of the thyroid gland itself. Thyroid Gland, endocrine gland found in almost all vertebrate animals and so called because it is located in front of and on each side of the thyroid cartilage of the larynx (see Endocrine System). It secretes a hormone that controls metabolism and growth. Excessive production of thyroid hormones, called hyperthyroidism or Graves' disease, results in elevated metabolism and activity. Deficiency of thyroid hormones, or hypothyroidism, is characterized by lethargy and lowering of metabolism.