Though the specific effects of the hormones secreted by the thyroid are various, their most important role in adults is regulating metabolic processes. In children, thyroid hormones also play an essential role in proper growth and development. Thus, a deficiency in thyroid secretion in childhood is associated with both dwarfism and mental deficiencies. Goiter, a disease characterized by the enlargement of the thyroid gland to such an extent that a sizable lump appears at the front of the neck making swallowing and breathing difficult, is also caused by inadequate levels of thyroxine. Hyperthyroidism, or excessive secretion by the thyroid, however, is most commonly manifested as Graves’ disease.