Dictionary

IORT Intraoperative radiation therapy.

iontophoresis A transdermal delivery system in which a substance bearing a charge is propelled through the skin by a low electrical current. This method can be used to drive a drug across the skin barrier.

IOM Institute of Medicine.

IOL Intraocular lens.

iodine excess Prolonged intake of too much iodine that leads to swelling of the thyroid gland (goiter) and abnormally low thyroid activity (hypothyroidism). Certain foods and medications contain large amounts of iodine, including seaweed; iodine-rich expectorants such as SSKI and Lugol’s solution that are used to treat cough, asthma, and chronic pulmonary disease; and amiodarone…

iodine deficiency A lack of sufficient iodine in the diet, which can lead to inadequate production of thyroid hormone (hypothyroidism) and enlargement of the thyroid gland (goiter). Since the addition of iodine to table salt became common, iodine deficiency has rarely been seen in the US.

iodine An element in the diet that is essential for the manufacture of hormones by the thyroid gland. The thyroid gland uses iodine to make thyroxine (T4), which has four iodine molecules attached to its structure, and triiodothyronine (T3), which has three iodine molecules attached. Iodine is found in seafood, bread, iodized salt, and seaweed.

iodide The form to which iodine in the diet is reduced before being absorbed through the intestinal wall into the bloodstream and carried to the thyroid gland. See also iodine.

involution A retrograde change. After treatment, a tumor may involute; with advancing age, there may be physical and emotional involution.

invest In medicine, to envelop, cover, or embed. For example, a dentist might invest a patient’s teeth with a wax material in order to form a mold of it.

inversion, chromosome See chromosome inversion.

invasive cancer Cancer that has spread from the site of origin to deeper tissues or to other parts of the body.