Efficacy and safety of radioiodine therapy for mild Graves ophthalmopathy depending on cigarette consumption: a 6‑month follow‑up.

INTRODUCTION    Graves ophthalmopathy (GO) is an autoimmune disease associated with Graves disease. Its treatment is largely dependent on the severity and activity of ocular lesions. Particular attention should be given to radioiodine (RAI) therapy. Although its use is a valuable therapeutic option for hyperthyroidism, it may be followed by worsening of GO.  OBJECTIVES    The aim of the present study was to analyze how the severity of nicotine addiction affects the response to RAI treatment in patients with GO. PATIENTS AND METHODS    A total of 106 patients (58 smokers and 48 nonsmokers) with mild GO treated with 800 MBq of RAI were included to the study. We assessed the serum levels of thyroid‑stimulating hormone (TSH), thyroid hormones, autoantibodies against thyroperoxidase, thyroglobulin, and TSH receptor (TSHR‑Abs), as well as urinary cotinine levels and severity of ophthalmopathy. Analyses were conducted at baseline (before RAI treatment) and 2 and 6 months after the therapy. RESULTS    Significant differences in serum levels of TSHR‑Abs were found between nonsmokers and smokers at 2 and 6 months after RAI therapy, whereas there were no differences at baseline. In smokers, there were significant differences in the severity of ophthalmopathy and the concentration of serum TSHR‑Abs assessed at baseline and at 6 months of follow‑up. Six months after RAI therapy, 46.2% of smokers and 4.3% of nonsmokers (P <0.001) progressed from mild to moderate GO.  CONCLUSIONS    High urinary cotinine levels in smokers were associated with the deterioration of ocular lesions after RAI treatment. A high dose of RAI did not induce an exacerbation of GO in nonsmokers who were administered oral steroid prophylaxis.