Hypothyroidism results from deficient production of thyroid hormone or a defect in the thyroid hormone receptor activity. hypothyroidism caused during embryonic development of the gland is called:

hyperthyroidism-an abnormally elevated blood level of thyroid hormones-is often caused by a pituitary or thyroid tumor. In Graves' disease, the hyperthyroid state results from an autoimmune reaction in which antibodies overstimulate the follicle cells of the thyroid gland.