Endocrine Abstracts (2011) 26 P432

The influence of radioiodine therapy on ophthalmologic symptoms and their relation to urine cotinine level in patients with Graves' disease

Agata Czarnywojtek1, Marek Ruchala1, Rafal Czepczynski1, Ewelina Szczepanek1, Ewa Florek2, Hanna Zamyslowska1, Izabela Kulinska-Niedziela3, Krzesislawa Komar-Rychlicka3 & Jerzy Sowinski1

1Department of Endocrinology, Metabolism and Internal Medicine, Poznan University of Medical Sciences, Poznan, Poland; 2Department of Toxicology, Poznan University of Medical Sciences, Poznan, Poland; 3Department of Ophthalmology, Poznan University of Medical Sciences, Poznan, Poland.

Introduction: Radioiodine therapy (RIT) in patients with Graves’ disease (GD) and orbitopathy (GO) is still controversial, especially in smokers, due to the risk of exacerbation of ophthalmologic symptoms.

Aim: To evaluate the effect of RIT in smoking and non-smoking patients with mild GO in a 6-month follow-up.

Patients and methods: We examined 26 smoking and 25 non-smoking patients, matched for age and gender, presenting hyperthyroidism and mild GO. In all patients, 22 mCi of radioiodine was administered, with subsequent protective 6-week oral prednisone therapy. The diagnostic procedures, performed at baseline and during follow-up included assessment of serum TSH, FT4 and anti-TSH receptor autoantibodies (TRAb) concentrations, urinary level of cotinine (marker of tobacco smoking) and thyroid ultrasound examination. Additionally, severity of GO was evaluated according to NOSPECS scale and Clinical Activity Scale (CAS). Patients presenting ≤4 points in NOSPECS scale and ≤3 in CAS were enrolled.

Results: TSH concentrations in both groups were undetectable. In smokers, FT4 levels before RIT was 22.2±3.9 and 18.6±6.1 pmol/l after 6 months, while in non-smokers, 22.9±3.1 and 18.8±4.1 pmol/l, respectively (P>0.05). TRAb concentration was higher in smokers (P<0.05) and increased from 22.9±7.2 IU/l before therapy to 28.9±10.6 IU/l after 6 months. In non-smokers, initial TRAb concentration was 15.3±6.2 and 15.2±6.8 IU/l after 6 months (P>0.05 for both groups). The CAS value in smokers before RIT increased from 2.8±0.2 points at baseline to 4.0±0.5 after 6 months, while in non-smokers was 1.4±0.2 and 2.2±0.2, respectively (P>0.05). The level of urine cotinine correlated positively with CAS and TRAb in smokers (P<0.05) at baseline and during the follow-up.

Conclusions: RIT with ablative dose of radioiodine and complementary oral prednisone therapy is safe in both smoking and non-smoking patients with mild GO. However, nicotinism was associated with increased severity of GO and TRAb at baseline and during follow-up.