I-125 uptake competing with iodine absorption by the thyroid gland following povidone-iodine skin application

Povidone-iodine solution is widely used to disinfect the skin surface or prevent suppuration during human and animal surgery. Using radioisotope I-125, we examined whether iodine may be absorbed and then concentrated in the thyroid gland when povidone-iodine solution is applied to the skin of rats or mice. The competition for I-125 uptake was examined in mice and rats after the application of povidone iodine to the skin. We also traced the process of absorbed I-125 in the thyroid gland during the fixation for tissue preparations. Povidone-iodine applied to the skin significantly reduced the uptake of I-125 both in mice and rats. Significant flux of I-125 from the thyroid gland in povidone-iodine treated animals was noted during the thyroid fixation of tissue preparations. From these results, povidone-iodine application to the skin instead of stable KI administration may be practical for preventing the uptake of I-125 by the thyroid gland during I-125 compound administration for medical therapy. In animal experiments concerning thyroid functions, careful attention must be paid when povidone-iodine is used for disinfection in animal surgery.