Association between radioiodine therapy for Graves’ hyperthyroidism and thyroid-associated ophthalmopathy

Abstract

To investigate the role of radioactive iodine (RAI) in the onset and progression of thyroid-associated ophthalmopathy (TAO). Forty-six Graves' disease patients with mild or no ophthalmopathy were prospectively treated with carbimazole (CBZ) (n = 22) or RAI (n = 24). Treatment effects were evaluated clinically over 12 months, and with orbital MRI-measured extra-ocular muscle (EOM) volumes at baseline and at 6 months. The diagnosis of TAO was based on the clinical activity score (CAS) system. There were 11/22 CBZ and 10/24 RAI patients with active ophthalmopathy at baseline. Despite greater mean TSH levels post-RAI (P = 0.003), there was no increase in the likelihood of developing active ophthalmopathy (OR 0.95; 95% CI 0.56-1.61, P = 0.9) or EOM dysfunction (OR 0.52; 95% CI 0.26-1.06, P = 0.074). The increased mean palpebral aperture post-RAI (P = 0.023) and greater mean proptosis in the CBZ group (P = 0.005) were not confirmed when the absolute values of these measurements were examined. There was no association between the treatment received and MRI-measured EOM volumes. In this study, RAI therapy for Graves' disease did not increase the risk of progression or development of ophthalmopathy in patients with mild or no eye disease at baseline.

Current Approach to Graves' Ophthalmopathy: Review

“…7 In some studies, exacerbations in ophthalmopathy have been shown in Graves' disease with the implementation of RAI. 8,9 There are some studies showing that concomitant implementation of corticosteroids with RAI therapy would be more appropriate in patients with ophthalmopathy (when severe cases excluded). 10 …”

Radioactive Iodine Therapy and Thyroid Eye Disease From an Ophthalmologist’s Perspective

“…13,25,37 Another study used the identical protocol but utilized 2 major criteria only (exophthalmometry and changes of Z2 points in CAS) 9 and yet another used items #1 to 7 and defined active TAO as CAS of Z4. 24 Another group used the full 10-item CAS and designated an increase of 2 points as progression. 23 Träisk et al 17 used their own ''Clinical TAO Assessment Score'' with TAO points from 0 to 3 in chemosis, eyelid edema, redness, Hertel increase, impaired eye movement, corneal involvement, and visual impairment.…”

“…Few studies blinded the examiner to the study variable (method of treatment, smoking status). 13,24,37 The effect of cigarette smoking on TAO has been well established and is known to be one of the most important and modifiable risk factors. Smokers have a higher risk of severe ophthalmopathy and there is a dose-dependent relationship, as well as temporality and reversibility, making smoking cessation counseling a crucial part of treating any patient with TAO.…”

Complications of Hyperthyroidism

“…Some different studies have shown improvement in TAO [173] by indirect beneficial effects [174] and a gradual decrease in TSHreceptor antibody (TRAb) levels during ATDs treatment [175]. There are confliciting reports in medical literature about RAI therapy and severe TAO [176,177]. But this association cannot be excluded.…”