Lassmann Michael, Luster Markus, Hänscheid Heribert, Reiners Christoph
Klinik und Poliklinik für Nuklearmedizin der Universität Würzburg, Würzburg, Germany.
J Nucl Med. 2004 Apr;45(4):619-25.
Recent publications described many discrepant findings about thyroid "stunning" after the administration of (131)I diagnostic activities to patients with differentiated thyroid carcinoma. Stunning may play a major role in reducing the therapeutic efficacy of high (131)I activities given for ablation therapy.
Participation in a multicenter study to investigate differences in iodine biokinetics in the hypothyroid state and after the application of recombinant human thyroid-stimulating hormone enabled us to study quantitative changes in thyroid iodine biokinetics after the administration of 74 MBq of (131)I twice within 6 wk and an ablation activity of 3-4 GBq 7-12 d after the second diagnostic administration of (131)I in 6 patients.
The uptake and half-life of the first 74 MBq of (131)I were significantly reduced to a mean of 44% and a mean of 51%, respectively, after the second diagnostic administration and further reduced to a mean of 40% and a mean of 30%, respectively, during ablation therapy. The residence times were reduced to 25% in the second dosimetric assessment and to 10% during therapy compared with the value in the first assessment. For one patient, an estimated absorbed dose as high as 38 Gy was found in the first diagnostic study. The mean dose for all patients after the first assessment was 15 Gy; after each further assessment, the dose was reduced according to the decrease in residence time.
This study shows a severe impact of 74 MBq of (131)I on the biokinetics of thyroid remnants during subsequent radioiodine therapy.
近期的出版物描述了许多关于分化型甲状腺癌患者接受（131）I诊断性检查后甲状腺“顿抑”的矛盾发现。顿抑可能在降低用于消融治疗的高活度（131）I的治疗效果方面起主要作用。
参与一项多中心研究以调查甲状腺功能减退状态下及应用重组人促甲状腺激素后的碘生物动力学差异，这使我们能够研究6例患者在6周内两次给予74 MBq的（131）I以及在第二次诊断性给予（131）I后7 - 12天给予3 - 4 GBq消融活度后甲状腺碘生物动力学的定量变化。
第二次诊断性给药后，首次74 MBq的（131）I摄取率和半衰期分别显著降至均值44%和均值51%，在消融治疗期间进一步分别降至均值40%和均值30%。与首次评估值相比，第二次剂量学评估时滞留时间降至25%，治疗期间降至10%。在一项患者的首次诊断研究中，发现估计吸收剂量高达38 Gy。首次评估后所有患者的平均剂量为15 Gy；每次进一步评估后，剂量根据滞留时间的减少而降低。
本研究表明74 MBq的（131）I对后续放射性碘治疗期间甲状腺残余组织的生物动力学有严重影响。
