Radioiodine Therapy Does Not Change the Atherosclerotic Burden of the Carotid Arteries.
Atherosclerosis evolves or accelerates when arteries are exposed to ionizing radiation, both early and late after exposure. Radioiodine therapy of benign thyroid disease exposes the carotid arteries to 4-50 Gy, and may thereby increase the risk of atherosclerosis. Increased risk of cerebrovascular events has been reported after radioiodine therapy. This study aimed to examine whether atherosclerosis develops early or late after radioiodine therapy of benign thyroid disease.



Patients treated for benign thyroid disorders (nontoxic goiter, adenoma, and hyperthyroidism) were examined with ultrasound for the main outcome, carotid intima media thickness (CIMT), and for plaque presence (plaque presence only in late damage). Signs of early damage from radioiodine were studied in 39 radioiodine-treated patients, who were examined before treatment and at 1, 3, 6, and 12 months after treatment. Late changes were studied in a cross-sectional case-control design, with radioiodine-treated patients as cases (n = 193) and patients treated with surgery as controls (n = 95). Data were analyzed with repeated measurement for longitudinal data, and with multivariate regression for cross-sectional data. Results were adjusted for age, sex, cholesterol, smoking status, known atherosclerotic disease, and body mass index.



No changes in CIMT were found in the patients followed prospectively for one year after treatment with radioactive iodine for benign thyroid disease (p = 0.58). In the study on late effects, there was no difference in CIMT (p = 0.25) or presence of plaques (p = 0.70) between those treated with radioactive iodine and those treated with surgery (9.8 and 5.6 years since treatment, respectively). Furthermore, the level of thyrotropin (TSH) did not influence these atherosclerosis markers.



No early changes in CIMT were detected in patients treated with radioactive iodine for benign thyroid disease. No signs of late effects of radioactive iodine on CIMT or plaque presence were found after 10 years of follow-up. The radiation to the carotid arteries by radioactive iodine therapy for benign thyroid disease may therefore have no or low effect on atherosclerotic burden of the carotid arteries in general.
1 Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen , Glostrup, Denmark .
Jeppe Lerche
JL
la Cour
1 Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen , Glostrup, Denmark .
Ulrik Bjørn
UB
Andersen
2 Department of ENT, Head & Neck Surgery and Audiology, Rigshospitalet/Gentofte University Hospital of Copenhagen , Hellerup, Denmark .
Christian Hjort
CH
Sørensen
3 Section of Endocrinology, Department of Medicine, University Hospital of Herlev , Herlev, Denmark .
Birte
B
Nygaard
4 Department of Clinical Physiology and Nuclear Medicine, University Hospital of Herlev , Herlev, Denmark .
Lars Thorbjørn
LT
Jensen
D000236:Adenoma / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging*; D059168:Carotid Intima-Media Thickness; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006042:Goiter / Q000532:radiotherapy*; D006801:Humans; D006980:Hyperthyroidism / Q000532:radiotherapy*; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging*; D011832:Radiation Injuries / Q000000981:diagnostic imaging*; D013964:Thyroid Neoplasms / Q000532:radiotherapy*; D014463:Ultrasonography
D007457:Iodine Radioisotopes