Hypothyroidism is a medical condition which is caused by insufficient production of thyroid hormones by the thyroid gland. Cretinism is a form of hypothyroidism found in infants.
The most common cause of hypothyroidism worldwide is iodine deficiency. In iodine-replete individuals hypothyroidism is generally caused by Hashimoto's thyroiditis, or otherwise as a result of either an absent thyroid gland or a deficiency in stimulating hormones from the hypothalamus or pituitary.
Other common cause of hypothyroidism is inflammation of the thyroid gland, which damages the gland's cells. As a result the pituitary gland does not secrete enough thyroid-stimulating hormone (TSH) to induce the thyroid gland to produce enough thyroxine and triiodothyronine.
The characteristic symptoms of hypothyroidism are: poor muscle tone (muscle hypotonia); fatigue; cold intolerance; increased sensitivity to cold; thin, brittle fingernails; thin, brittle hair; depression; decreased sweating; muscle cramps and joint pain.
Treatment: hypothyroidism is treated with the levorotatory forms of thyroxine (L-T4) and triiodothyronine (L-T3). Both synthetic and animal-derived thyroid tablets are available and can be prescribed for patients in need of additional thyroid hormone. Thyroid hormone is taken daily, and doctors can monitor blood levels to help assure proper dosing.