Metabolism of Oral Iodide and 3,5-Diiodosalicylic Acid in the Pregnant Cow

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Abstract
TWO near-term pregnant cows were each given simultaneous oral tracer doses of I131 as 3,5-diiodosalicyllc acid (DI131S) and I125 as iodide. A 3rd cow was given both radioisotopes as iodide. For animals given DI131S, percentages of doses of each isotope excreted (urinary and Jecal) in 144 hr were 83.6 for I131 and 43.1 for I125, Average percentages of the doses in ttacoids at sacrifice were: maternal thyroid I131, 2.3; fetal thyroid I131, 2.1; maternal thyroid I125, 18.0; and fetal thyroid I125, 15.9, iodine fed as DE was not as available to either maternal or fetal thyroids and did not cross the placenta as readily as iodine fed as iodide. The animal given both isotopes as iodide exhibited no differences between the 2 isotopes in excretion or in concentrations in various tissues.