A gamma camera re-evaluation of potassium iodide blocking efficiency in mice.
The protection of the thyroid against radioiodine uptake has been an important safety concern for decades. After several studies examined potassium iodide blockade efficacy in the 1960's and 1970's, a standard dosage was prescribed by both the World Health Organization and the U.S. Food and Drug Administration. In this paper, we tested the effectiveness of a scaled version of that standard dosage in comparison to higher doses in mice. A novel gamma camera was employed with a high spatial resolution for precisely quantifying activity within the thyroid and a field of view large enough to image the entire mouse body. Thyroid and whole-body 125I biodistribution was analyzed immediately after exposure and 1 and 7 days later. It was found that 1 h after exposure five times the scaled human dose blocked thyroid uptake about 40% more effectively than the 1X scaled dose. Even after 1 d and 7 d, five times the recommended scaled human dose blocked approximately 10% more effectively than the 1X dose. These data suggest the need for continued evaluation of the effectiveness of KI as a blocking agent and the application of novel, non-invasive technologies to this important human health issue.
Hammond
William T
WT
Department of Physics, College of William and Mary, Williamsburg, VA 23185, USA.
Bradley
Eric L
EL
Welsh
Robert E
RE
Qian
Jianguo
J
Weisenberger
Andrew G
AG
Smith
Mark F
MF
Majewski
Stan
S
Saha
Margaret S
MS
D000284:Administration, Oral; D000818:Animals; D015902:Gamma Cameras; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D011193:Potassium Iodide / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011833:Radiation Injuries, Experimental / Q000517:prevention & control / Q000662:veterinary; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics / Q000627:therapeutic use; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism; D014018:Tissue Distribution / Q000187:drug effects* / Q000502:physiology; D014915:Whole-Body Counting
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D011193:Potassium Iodide