The Prevalance of Thyroid Autoantibodies in Patients with Rheumatoid Arthritis

Background: Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder that affects approximately 0.5-1% of the population and according to general opinion the frequency of systemic autoimmune disorders to be seen together with organ specific autoimmune disorders is not very common. The aim of this study was to evaluate the thyroid functions and thyroid autoantibodies in patients with RA and to determine the frequency of autoimmune thyroid disorders in these patients. Materyal and Method: 82 active patients (67 females and 15 males) with a diagnosis of RA according to 1987 ARA classification criteria were included in the study. 47 healthy individuals (31 females and 16 males) were included in the study as the control group. In all participants free thyroxine (fT4), free triiodothyronine (fT3), thyrotropin (TSH), thyroglobulin antibody (anti-Tg) and anti-peroxidase (anti-TPO) antibody titres were measured. Results of the RA patients were compared with the controls. Results: In the RA group thyroid autoantibody values were as follows: anti-TPO 85.69 106.83 IU/ml and anti-Tg 58.2 83.9 IU/ml. These values were: anti-TPO 43.16 132.23 IU/ml and anti-Tg 24.19 36.74 IU/ml in the control group. There was a statistically significant difference between two groups with regards to thyroid autoantibodies (p=0.008, p=0.0004, respectively). There was not any statistically significant difference between two groups with regards to fT3, fT4 and TSH values (p> 0.05). Conclusion: As there was not an apperent finding specific for a thyroid disorder in patients with RA in our study, the thyroid antibody positivity identified here might be due to a pathologic autoimmune response rather than demonstrating a thyroid disease.Thyroid function and TPO Ab tests should be performed as part of the biochemical and immunological profile in RA patients.