protein-bound iodine

iodine /io·dine/ (I) (i´ah-dīn) chemical element, at. no. 53; it is essential in nutrition, being necessary for synthesis of the thyroid hormones thyroxine and triiodothyronine. Iodine solution is used as a topical antiinfective. See also radioiodine.

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protein-bound iodine  iodine firmly bound to protein in the serum, determination of which constitutes one test of thyroid function.

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protein-bound iodine

n. Abbr. PBI

Thyroid hormone consisting of one or more of the iodothyronines bound to one or more of the serum proteins.

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iodine (I) (ī´dīn´),

n a halogen element that is nonmetallic in nature; atomic weight is 126.91. As a nutritional element, iodine is vital to the production of thyroxin by the thyroid gland. In radioactive form, iodine is used as a diagnostic substance to determine the ability of the thyroid gland to take up iodine. In tincture form, iodine is used as a locally applied antiseptic, germicide, and disclosing solution.

iodine number,

n the amount of iodine absorbable by 100 g of a fat or an oil; the lower the level of unsaturated fatty acids in the fat or oil, the higher the iodine number.

iodine, protein-bound (PBI),

n the iodine bound to protein, mainly thyroxin in the plasma. The thyroid hormone is precipitated by protein-denaturing agents, and, in general, the amount of iodine in a protein precipitate indicates the amount of thyroid hormone present and is thus an index of thyroid activity. Various values are given for thyroid function: hypothyroidism, 0 to 3.5 mg/ml of protein-bound iodine; euthyroidism, 3.5 to 8 mg/ml; hyperthyroidism, values higher than 8 mg/ml.

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iodine

a chemical element, atomic number 53, atomic weight 126.904, symbol I. See Table 6. Iodine is essential in nutrition, being especially prevalent in the colloid of the thyroid gland. It is used in the treatment of hypothyroidism and as a topical antiseptic. Iodine is a frequent cause of poisoning. See also iodism.

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iodine-125

a radioisotope of iodine having a half-life of 60 days and a principal gamma-ray photon energy of 28 keV; used as a label in radioimmunoassays and other in vitro tests, and also for thyroid imaging. Symbol ¹²⁵I.

¹²³iodine-metaiodobenzylguanidine

a radioisotope which concentrates in chromaffin cells; used in diagnostic scintigraphy, e.g. in cases of pheochromocytoma.

iodine-131

a radioisotope of iodine having a half-life of 8.1 days and a principal gamma-ray photon energy of 364 keV; used in treatment of hyperthyroidism and carcinoma of the thyroid, in thyroid function testing, and in imaging of the thyroid gland and other organs. Symbol ¹³¹I.

iodine deficiency

may occur in all species under certain conditions; in dogs and cats, a factor in all-meat diets. See also goiter.

iodine contrast agents

iodine salts are opaque to x-rays; therefore they can be combined with other compounds and used as contrast media in diagnostic x-ray examinations.

iodine nutritional deficiency

is characterized by goiter, neonatal mortality and alopecia.

iodine poisoning

occurs usually due to accidental overdosing. It causes lacrimation, anorexia, coughing due to bronchopneumonia, and a heavy dandruff. Paradoxically, iodine excess may result in thyroid hyperplasia and goiter, especially in the young.

protein-bound iodine

a test of thyroid function. See also protein-bound iodine (PBI) test.

radioactive iodine

see iodine-125, iodine-131 (above).

iodine residues in milk

careless use of iodine-based teat dips results in unacceptable residues of iodine in milk.

iodine solution

contains 2% free iodine and 2.4% sodium iodide in an aqueous solution.

iodine solution (strong)

contains 5% free iodine and 10% potassium iodide in an aqueous solution.

tamed iodine

see iodophor.

iodine trapping

the selective absorption of iodine from the circulation by the thyroid gland.