Hypothyroidism is the underactivity of the thyroid gland,this is when the thyroid produces less hormones then expected known ashypo-secretion, which causes a slow metabolism due to hypo-responsiveness oftarget cells. Hypothyroidism is an endocrine disorder which can be divided intoprimary which is caused by diseases in the target glands or secondary which is causedby diseases in the pituitary gland. There are two main causes of hypothyroidismthe first being autoimmune and the second is post-therapeutic. There are threedifferent types of hypothyroidism such as primary (Giotrous) hypothyroidism,the common causes for this is Hashimoto (an autoimmune disease), endemic iodinedeficiency, postpartum thyroiditis, subacute thyroiditis and drug induce suchas treatment for hyperthyroidism which may lead to hypothyroidism.
The commoncauses for primary (non-goitrous) hypothyroidism include; surgical ablation, radioactiveiodine therapy, atrophic myxedema, external radiation and sporadic critinism.The common cause for secondary hypothyroidism include; pituitary disease due tolow secretion of TSH and hypothalamic disease, this happens when thehypothalamus produces an inadequate amount of thyrotropin-releasing hormone(TRH). There are other further common causes of hypothyroidism include diet,congenital dysfunction, chemical exposure, lack of T4 being converted to T3.