Nutritional Laboratory, Department of Medical Biochemistry, Clinic of Laboratory Medicine, Oslo University Hospital Aker; University of Oslo, Oslo, Norway.
Department of Radiology, Medical Clinic, Oslo University Hospital Aker, Norway.
Scand J Clin Lab Invest. 2020 May;80(3):191-195. doi: 10.1080/00365513.2019.1709658. Epub 2020 Jan 28.
Excess of iodine may interfere with thyroid function. It is unclear to what extent the thyroid function is disturbed by repeated infusion of iodide contrast agent (IC) used during X-ray examinations. Thyroid function tests free T4 (FT4), free FT3 (FT3), thyroid-stimulating hormone (TSH), TSH receptor antibodies (TRAb) and thyroid peroxidase antibodies (TPO-Ab) were measured in a group of Norwegian patients with an assumed normal iodine balance before, 1 and 6 weeks after IC infusion. Forty patients (19 females and 21 men) referred for routine CT were included. Thirty two out of 40 patients had previously undertaken IC investigations. The mean TSH concentration was 2.1 mIU/l ± 1.7 at the baseline, increased to 2.9 ± 2.5 after 1 week ( < .001), and reverted to nearly initial values 1.4 ± 0.8 after 6 weeks. Initially the mean FT4 was 14.1 pmol/l ± 1.9 FT4, reduced to 13.3 pmol/l ± 2.5 ( = .009) after 1 week, and returned to 14.0 pmol/l ± 2.5 after 6 weeks, comparable to the initial values ( > .05). FT3 levels did not change during the period. There was no relationship between FT4, or TSH and age, gender, cancer/not cancer, number or frequency of earlier IC investigations. In conclusion, IC induces changes in thyroid function tests, however, they return to normal levels after 6 weeks. Our results suggest adequate auto regulatory capacity of the thyroid gland even in those with repeated contrast investigations (up to 40). Routine testing of thyroid function should therefore not be undertaken in this patient group.
碘过量可能会干扰甲状腺功能。目前尚不清楚在 X 射线检查中反复输注碘化物对比剂（IC）会在多大程度上扰乱甲状腺功能。在一组假定碘平衡正常的挪威患者中，在 IC 输注前、1 周和 6 周时测量了游离 T4（FT4）、游离 FT3（FT3）、促甲状腺激素（TSH）、促甲状腺激素受体抗体（TRAb）和甲状腺过氧化物酶抗体（TPO-Ab）。40 名因常规 CT 检查而就诊的患者（19 名女性和 21 名男性）纳入本研究。40 名患者中有 32 名之前曾接受过 IC 检查。基线时 TSH 浓度平均值为 2.1 mIU/l±1.7，1 周后增加至 2.9 mIU/l±2.5（ < .001），6 周后恢复到接近初始值 1.4 mIU/l±0.8。最初，FT4 的平均值为 14.1 pmol/l±1.9 FT4，1 周后降至 13.3 pmol/l±2.5（ = .009），6 周后恢复至 14.0 pmol/l±2.5，与初始值相当（ > .05）。FT3 水平在该期间内无变化。FT4 或 TSH 与年龄、性别、癌症/非癌症、先前 IC 检查的次数或频率之间无相关性。总之，IC 会引起甲状腺功能测试的变化，但在 6 周后会恢复到正常水平。我们的结果表明，即使在反复进行造影检查（多达 40 次）的患者中，甲状腺也具有足够的自动调节能力。因此，在该患者群体中不应常规进行甲状腺功能检测。
