Objective: Graves’ disease (GD) is characterized by elevated TSH-receptor antibodies (TRAb) and less often – thyroid peroxidase (TPOAb) and thyroglobulin antibodies (TgAb). Our aim was to examine the hormonal and ultrasound characteristics of patients with newly diagnosed GD with differing positive thyroid antibodies. Materials and Methods: This study included 249 patients with newly diagnosed GD (191 women, 58 men). 40.2% of them had Graves’ ophtalmopathy. The serum levels of TSH, free T4, free T3, TRAb, TPOAb, and TgAb were measured with third generation ECLIA assays (Roche Diagnostics, Switzerland). Thyroid ultrasound was performed with a Fukuda-Denshi 550 device (Fukuda Corp., Japan) and an Ultrasonix device (Ultrasonix Medical Corp., Canada). Statistical analyses were done using the SPSS 23.0 statistical package (Chicago, IL). Results: 64% of the patients were TPOAb+ and 36% − TgAb+. One third were only TRAb+, 1/3 had two positive antibodies (TRAb + second antibody) and 1/3 – all three positive antibodies. Patients with more positive antibodies tended to be younger, had higher fT4, TRAb levels, thyroid volume but rarely had nodules on US and accompanying GO. Positive TPOAb antibodies were found in younger patients, with higher fT4 and TRAb levels, higher thyroid volume and lower prevalence of nodules and GO. The same trends were found in patients with positive TgAb. Conclusion: The different characteristics of GD patients with varying thyroid antibody profiles may be due to a variation in the pathogenesis of the disease. An individualized clinical approach may be suitable in those cases.

Objective: The current understanding regarding the clinical significance of TSH receptor antibodies in chronic autoimmune thyroiditis is controversial. The aim of this study was to examine the frequency of elevated TSH receptor antibodies in euthyroid and hypothyroid autoimmune thyroiditis. Furthermore, their associations with the levels of thyroid hormones and autoantibodies (thyroid peroxidase and thyroglobulin antibodies [TgAb]), and the thyroid volume were also investigated. Material and Methods: This cross-sectional study included recently diagnosed euthyroid (N=86) and hypothyroid (N=54) autoimmune thyroiditis patients along with the patients who were on levothyroxine replacement (N=66). The levels of TSH, free T4, free T3, TSH receptor antibodies, thyroid peroxidase, and thyroglobulin antibodies were measured using ECLIA (Roche Diagnostics, Switzerland). A 9 MHz transducer (Fukuda Corp., Japan) for thyroid ultrasound and a 14 MHz transducer (Ultrasonix Medical Corp., Canada) for Doppler ultrasound were employed. Statistical analyses were done with the help of IBM SPSS 19.0 software. Results: The elevated levels of TSH receptor antibodies were observed in 6.3% of the participants (12 females and 1 male) and exclusively in hypothyroid subjects, who were either untreated (7.4%) or on levothyroxine treatment (7.6%). The highest and the lowest prevalence of positive TSH receptor antibodies were seen in patients with positive thyroglobulin antibodies & negative thyroid peroxidase (17.6%) and positive thyroid peroxidase & negative thyroglobulin antibodies (3.3%), respectively. Higher levels of TSH receptor antibodies were associated with a shorter duration of the disease (22 vs. 36 months), lower titers of thyroglobulin antibodies (281.2 vs. 400.9 UI/L), decreased thyroid volumes (9.4 vs. 14.2 cm 3) and an increased prevalence of orbitopathy (23.1 vs. 4.1%). In the whole study population, TSH receptor antibodies levels were related to fT4 (linear R2=0.271, p=0.039), titers of thyroid peroxidase (quadratic, R2=0.048, p=0.034), and thyroid volume (compound R2=0.041, p=0.011). However, in the TSH receptor antibodies positive patients, the correlation was seen only with the levels of thyroid peroxidase (compound R2=0.503, p=0.032). Conclusion: TSH receptor antibodies positivity cannot be considered negligible in Hashimoto's thyroiditis. The elevated levels of TSH receptor antibodies might result in a predisposition to a more unstable thyroid function, lower thyroid volumes, specific profiles of thyroid peroxidase, and thyroglobulin antibodies and a higher prevalence of thyroid-associated ophthalmopathy.

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