Endocrine Abstracts (2011) 26 P443

Long-term follow-up of thyroid autoimmunity biomarkers in Graves' disease treated with low dose anti-thyroid medications (interim report)

H R Bazrafshan1,2, F Fitz1, M Steinmair1, S Haim1, C Reichl1, M Beheshti1, W Langsteger1 & L Klesov1


1Department of Nuclear Medicine and Endocrinology, PET-CT Center Linz, St Vincent’s Hospital, Linz, Austria; 2Department of Endocrinology, Golestan University of Medical Sciences, Gorgan, Islamic Republic of Iran.


Background: There are remarkable debates on the pathogenic mechanisms of Graves’ disease (GD). We prospectively followed up the serum levels of different autoimmunity indices in patients with GD in order to elucidate their pattern of alteration with time.

Methods: A total of 119 consecutive patients with GD were treated using low dose anti-thyroid medications at the initial dose of 20 mg/day of methimazole (MMI). Then, the dose was gradually decreased, when the patients were able to the minimum maintenance dosage of 5 mg MMI or or 25 mg PTU and finally discontinued in euthyriod patients after one year. During the treatment and also after the discontinuation of the drugs, the thyroid hormones (FT3, FT4, and TSH) and thyroid auto-antibodies (anti-TPO, anti-TSHRab and anti-Tg) were measured routinely every 4 weeks for the first 3 months and every 3 months. Follow-up period was up to 10 years.

Results: The mean reductions of anti-TPO, anti-TSHRab and anti-Tg during the follow-up period were 6, 35.8 and 59.6%, respectively. Euthyroid status was achieved in 25.2, 26.1, 37, 45.4, 51.3, 52.9 and 47.9% in 3rd, 6th, 9th, 12st, 24nd, 60th and 120th month follow-ups, respectively. No significant correlation was found between the reductions in serum concentrations of anti-TSHRab and anti-TPO as well as anti-TSHR ab and anti-Tg and also anti-TPO and anti-Tg.

Conclusion: Low dose anti-thyroid medications reduce the serum concentrations of thyroid autoimmunity biomarkers during years, which can be considered as an indirect evidence for their immunosuppressive effects. Unparallel pattern of reduction of these thyroid auto-antibodies suggest the presence of different pathologic mechanisms and independent autoimmunity routes for GD.

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