Osmium (from Greek á½ÏÎ¼Î® osme, smell) is a chemical element with symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element, with a density of 7004225900000000000â 22.59 g/cm3. Its alloys with platinum, iridium, and other platinum-group metals are employed in fountain pen nibs, electrical contacts, and other applications where extreme durability and hardness are needed.
Goiter is a noncancerous enlargement of the thyroid gland. The most common cause of goiter worldwide is iodine deficiency in the diet. Goiter is often caused by (and a symptom of) hyperthyroidism in the United States, where iodized salt provides plenty of iodine.
The most common type of hypothyroidism is that caused by primary thyroid gland failure. Basic causes of primary hypothyroidism are autoimmune, silent, postablative, goitrous, athyreotic and nonautoimmune (e.g., Riedel's), and subacute thyroiditis. Chronic autoimmune lymphocytic thyroiditis (Hashimoto's disease) is the most common cause of thyroid gland dysfunction. Replacement of lacking thyroid hormones reduces high blood pressure (BP) and total cardiovascular risk. Similar effects have also been described in subclinical hypothyroidism.