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.
Autoimmune reactions against the thyroid can cause hyperthyroidism; Graves' disease is one such condition. The immune system malfunctions, causing an increase in thyroid hormone. Goiter, a greatly enlarged thyroid gland, is seen in those with Graves' disease and is due to the excessive secretion of thyroid hormone.utoimmune reactions against the thyroid can cause hyperthyroidism; Graves' disease is one such condition. The immune system malfunctions, causing an increase in thyroid hormone. Goiter, a greatly enlarged thyroid gland, is seen in those with Graves' disease and is due to the excessive secretion of thyroid hormone.