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.
In spite of this the thyroid gland continues to grow and make thyroid hormone. Therefore, Gravesâ disease produces a goiter and hyperthyroidism. Multinodular goiters are another common cause of goiters. Individuals with this disorder have one or more nodules within the gland which cause thyroid enlargement. This is often detected as a nodular feeling gland on physical exam. Patients can present with a single large nodule or with multiple smaller nodules in the gland when first detected (see Thyroid Nodule brochure). Thus, in early stages of a multinodular goiter with many small nodules, the overall size of the thyroid may not be enlarged yet. Unlike the other goiters discussed, the cause of this type of goiter is not well understood. In addition to the common causes of goiter, there are many other less common causes.