Phan Guillaume, Rebière François, Suhard David, Legrand Alexandre, Carpentier Floriane, Sontag Thibaud, Souidi Maâmar, Jourdain Jean-René, Agarande Michelle, Renaud-Salis Valérie
Health Division, Institute for Radiation Protection and Nuclear Safety, Paris, France.
Dose Response. 2017 Dec 13;15(4):1559325817746558. doi: 10.1177/1559325817746558. eCollection 2017 Oct-Dec.
A dose-response study was performed in adult rats to select an optimal stable potassium iodide (KI) dose which could be implemented in repeated prophylaxis, in case of prolonged exposure to radioactive iodine. Increasing doses of KI were given orally to rats 1 hour before internal exposure simulated by I-125 injection. I-125 incorporation in the thyroid was measured by γ-spectrometry, and KI protection effect was modeled by pharmacological functions. The measurement method by inductively coupled plasma mass spectrometry previously developed for the quantification of stable iodine in urine was adapted to correlate KI effect with its distribution in the thyroid. More than 75% blockade of iodine I-125 incorporation in the thyroid was achieved for KI single doses above 0.5 to 0.7 mg/kg. Stable iodine content in the thyroid 24 hours after KI administration displayed a biphasic response, with a maximum level for a dose around 1 mg/kg. Besides, the urinary excretion of stable iodine is described by a sigmoid function. The change in the rate of iodine excretion for doses above 1 mg/kg KI suggests a body overload in iodine and corroborates a possible saturation of the thyroid. The results show that 1 mg/kg KI could be regarded as an optimal dose for thyroid protection.
在成年大鼠中进行了一项剂量反应研究，以选择一种最佳的稳定碘化钾（KI）剂量，以便在长期暴露于放射性碘的情况下用于重复预防。在通过注射I-125模拟内照射前1小时，给大鼠口服递增剂量的KI。通过γ能谱法测量甲状腺中I-125的掺入量，并通过药理函数对KI的保护作用进行建模。先前开发的用于定量尿液中稳定碘的电感耦合等离子体质谱测量方法经过调整，以关联KI效应与其在甲状腺中的分布。对于高于0.5至0.7mg/kg的KI单剂量，甲状腺中I-125掺入量的阻断率超过75%。KI给药后24小时甲状腺中的稳定碘含量呈现双相反应，剂量约为1mg/kg时达到最高水平。此外，稳定碘的尿排泄可用S形函数描述。KI剂量高于1mg/kg时碘排泄率的变化表明体内碘过载，并证实甲状腺可能饱和。结果表明，1mg/kg KI可被视为保护甲状腺的最佳剂量。
