hormonal and metabolic disorders
Hyperthyroidism
Causes of Hyperthyroidism
Themost commoncauses include Graves disease Toxic multinodular goiter Thyroiditis Single toxic nodule the most common cause of hyperthyroidism, is an Autoimmune Disorders . In an autoimmune disorder, the person's immune system produces antibodies that attack the body's own tissues. Usually, the antibodies damage cells and worsen their ability to function. However, in Graves disease, the antibodies stimulate the thyroid to produce and secrete excess thyroid hormones into the blood. This cause of hyperthyroidism is often hereditary and almost always leads to enlargement of the thyroid. Toxic multinodular goiter(Plummer disease), in which there are many nodules (small lumps), one or more of which may start to produce and secrete excess thyroid hormone. This disorder is more common with aging but is uncommon in adolescents and young adults. Atoxic (overactive) thyroid nodule(a benign tumor, or adenoma) is an area of abnormal local tissue growth within the thyroid gland. This abnormal tissue produces thyroid hormones even without stimulation by thyroid-stimulating hormone (TSH, a hormone produced by the pituitary gland to stimulate the thyroid gland to produce thyroid hormones). Thus, a nodule escapes the mechanisms that normally control the thyroid gland and produces thyroid hormones in large quantities. is inflammation of the thyroid gland. The inflammation can be caused by a viral infection ( Subacute Thyroiditis ), autoimmune thyroid inflammation that occurs after childbirth ( Other causesof hyperthyroidism include Some medications, including too much thyroid hormone taken orally Rarely overstimulation due to an overactive pituitary gland Medications and iodinecan cause hyperthyroidism. Medications includeamiodarone, interferon-alpha, programmed death receptor-1 (PD-1) inhibitors (such asnivolumabandpembrolizumab),alemtuzumab, and, rarely,lithium. Excess iodine, as may occur in people taking certain expectorants, or in those given iodine-containing contrast agents for x-ray studies, may cause hyperthyroidism in people with a nodule that has escaped the control of thyroid-stimulating hormone and has the capacity to make large quantities of thyroid hormone when presented with excess iodine, thus becoming a toxic thyroid nodule. Taking too much thyroid hormone orally can also cause hyperthyroidism, and is one of the most frequent causes of a low TSH or an elevated T4 level. An overactive pituitary glandcan produce too much thyroid-stimulating hormone, which in turn leads to overproduction of thyroid hormones. However, this is an extremely rare cause of hyperthyroidism. 