Impact of Radioiodine Treatment on Doppler Flow Parameters in the Central Retinal Artery and Ophthalmic Artery in Patients With Hyperthyroidism

Abstract

Objectives The aim of this study was to identify changes in Doppler flow parameters in the central retinal artery (CRA) and ophthalmic artery (OA) that could be indicative of de novo development of thyroid‐associated orbitopathy in the early period after radioiodine treatment. Methods Eighty‐two patients with hyperthyroidism were enrolled: 44 with Graves disease and 38 with toxic nodular goiter. In both groups, blood flow parameters in the CRA and OA were analyzed before and 2 and 4 weeks after radioiodine administration. The peak systolic velocity and end‐diastolic velocity (EDV) were evaluated, and the resistive index (RI) was calculated. Results There were no statistically significant differences in the peak systolic velocity, EDV or RI between groups at baseline and 4 weeks after radioiodine administration. Two weeks after radioiodine administration, the RI in the CRA (P = .034) and EDV in the OA (P = .026) were significantly lower, and the EDV in the CRA (P = .004) was higher in patients with Graves disease than in patients with toxic nodular goiter. There was an inverse correlation between baseline thyrotropin receptor autoantibody (TRAb) levels and the difference between the RI at weeks 4 and 2 (RI3‐RI2) in the CRA (r = −0.458; P < .05) and a positive correlation between the baseline anti‐thyroid peroxidase antibody concentration and RI3‐RI2 in the OA (r = 0.435; P < .05). Conclusions Administration of radioiodine results in more prominent features of hyperkinetic circulation. Patients with Graves disease and high TRAb titers have a lower sensitivity to radioiodine treatment. High TRAb titers suggest higher disease activity and a weaker therapeutic effect of radioiodine.