Abstract
Aim: The radiation can induce vessel injury. The result of this injury can be severe and life-threatening. There are a few studies demonstrating an increase in intima-media thickness (IMT) of the common carotid artery (CCA) after radiotherapy, especially in head and neck cancers. We evaluated the effect of I-131 to the IMT of the CCA in the patients who were treated for hyperthyroidism.Methods: 38 patients (25M, 13W) referred to our department for radioiodine treatment with the diagnosis of nodular goitre (25 patients) and diffuse hyperplasia (Graves disease (GD), 13 patients) were included to the prospective study. An USG was performed for all the patients before therapy, 3, 6 and 12 months after radioiodine therapy in order to measure IMT of CCA and the femoral artery (FA). The IMT was measured at the level of proximal part of bulbus anteriorly on the left and right side. The IMT of FA was measured just before the bifurcation.Results: There was a statistically significant increase in IMT of both CCA and FA bilaterally in nodular hyperthyroid patients. However, in the patients with Graves disease, there was only statistically significant increase in the left IMT of CCA at 0-3rd, 0-6th month measurements and in the right IMT of FA at 0-3rd month measurements. Conclusion: Though the limitation of the study is the interobserver and intraobserver variability, it was seen that I-131 therapy might affect the IMT of CCA in the patients with NG. I-131 effect on the IMT of CCA in patients with nodular goitre was higher than the IMT of CCA in patients with GD. I-131 effect on the IMT of CCA might be due to administered dose and adjacency. The interesting point of our study was the increased thickness of IMT in FA. We think that the increase in IMT is due to the systemic effect of radioactivity circulating in the blood vessel. I-131 effect on the IMT of FA in patients with nodular goitre was higher than the IMT of FA in the patients with GD due to I-131 uptake of thyroid gland. Because I-131 uptake was lower in patients with nodular goitre, I-131 in systemic circulation was higher.Conflict of interest:None declared.
Highlights
It was shown that therapeutic radiation exposure cause damage to the carotid and other large vessels in the world literature since the 1950s [1,2,3]
Patients 38 patients (25M, 13W) were evaluated for the intima media thickness (IMT) of carotid and femoral artery. 25 of 38 (66%) patients had nodular goitre (NG) and 13 of 38 (34%) patients had GD. 12 of 25 patients had nodule in the left thyroid lobe, 9 of 25 patients had nodule in the right thyroid lobe and 4 of 25 patients had nodules in bilateral thyroid lobes
The IMT of right carotid artery increased from 0.84±0.20 to 0.90±0.20 (p=0.028); the IMT of left carotid artery increased from 0.88±0.22 to 0.94±0.23 (p=0.033); the IMT of right femoral artery increased from 0.96±0.24 to 1.06±0.26 (p=0.001); the IMT of left femoral artery increased from 0.97±0.26 to 1.07±0.25 (p=0.009) in patients with NG at the end of 12th month
Summary
It was shown that therapeutic radiation exposure cause damage to the carotid and other large vessels in the world literature since the 1950s [1,2,3]. Radioiodine is in most cases the first-line treatment for solitary hyperfunctioning thyroid nodules. It is used in uncontrolled hyperthyroidism and Graves’ disease. Our hypothesis is beta radiation can cause damage to the adjacent vessels of thyroid lobe while killing hyperfunctioning thyroid cells. We investigated the effect of radioiodine on the intima media thickness (IMT) of the carotid artery. This is the first prospective study to evaluate the effects of radioiodine on the carotid artery wall in the literature
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