Thyroid gland. Computer artwork of the thyroid gland (pink). This two-lobed, endocrine gland is found in the neck, where it lies on top of the trachea (windpipe, centre). The thyroid gland opens directly into the bloodstream, secreting the hormones thyroxine, triiodothyronine and calcitonin. These hormones regulate energy levels and body metabolism, and are vital for normal mental and physical development in children. A lack of these hormones may cause cretinism in infants and myxoedema (thickening of the skin and other tissues) in adults.