School of Veterinary Science, Massey University, Palmerston North, New Zealand.
The Royal (Dick) School of Veterinary Studies and the Roslin Institute, The University of Edinburgh, Roslin, United Kingdom.
J Vet Intern Med. 2021 Jul;35(4):1697-1702. doi: 10.1111/jvim.16185. Epub 2021 Jun 6.
Injectable radioactive iodine (I-131) frequently is used to treat hyperthyroidism in cats. In human medicine, residual activity after injection of radionuclides has been reported, and the actual quantity administered is recorded after administration.
Our aim was to evaluate actual administered dose variability after administration of preprepared I-131 single unit doses for the treatment of hyperthyroidism in cats.
Twenty-seven cats with hyperthyroidism treated with I-131 between April 2017 and March 2019.
Retrospective observational study of cats treated with preprepared single unit I-131 doses. For each dose, the measured activity before administration and residual activity were recorded. The measured dose and the actual dose administered were compared to the prescribed dose.
Measured activity before administration ranged from 88.4% to 103.3% of the prescribed dose. Mean residual activity was 5.2 ± 3.0 MBq (ranging from 1.5% to 15% of the prescribed dose). The actual dose administered (measured activity - residual activity) ranged from 79.1% to 100.2% of the prescribed dose. Seventeen of 28 (60.7%) of the actual administered doses differed between 10% and 20% of the prescribed dose. One administered dose had a >20% difference compared to the prescribed dose (79.10% of the prescribed dose).
Our study identified variability in the residual and actual administered activity of I-131 as compared to the prescribed dose, which should be taken into consideration when treating cats with (predrawn) I-131.
注射用放射性碘（I-131）常用于治疗猫的甲状腺功能亢进症。在人类医学中，已经报道了注射放射性核素后残留的活性，并且在给药后记录实际给予的量。
我们的目的是评估预先制备的 I-131 单剂量单位治疗猫甲状腺功能亢进症后给予的实际剂量的变异性。
2017 年 4 月至 2019 年 3 月期间接受 I-131 治疗的 27 只患有甲状腺功能亢进症的猫。
对接受预先制备的 I-131 单剂量单位治疗的猫进行回顾性观察性研究。对于每个剂量，记录给药前的测量活性和残留活性。将测量剂量和实际给予剂量与规定剂量进行比较。
给药前的测量活性范围为规定剂量的 88.4%至 103.3%。平均残留活性为 5.2±3.0 MBq（占规定剂量的 1.5%至 15%）。实际给予的剂量（测量的活性-残留活性）范围为规定剂量的 79.1%至 100.2%。28 个实际给予剂量中的 17 个（60.7%）与规定剂量相差 10%至 20%。一个给予的剂量与规定剂量相差>20%（规定剂量的 79.10%）。
我们的研究发现，与规定剂量相比，I-131 的残留和实际给予的活性存在差异，在使用（预先绘制的）I-131 治疗猫时应考虑到这一点。
