Abstract
Introduction: Ankylosing spondylitis (AS) is a chronic inflammatory disease. Thyroid dysfunctions are more frequent in patients with inflammatory diseases. In this study, we aimed to evaluate thyroid functions and thyroid autoantibodies in ankylosing spondylitis patients, to determine the effect of anti-tumor necrosis factor treatment in AS patients and the relationship between thyroid function and autoantibody levels, inflammatory markers and disease activity in ankylosing spondylitis patients.
Materials and Methods: 74 ankylosing spondylitis patients diagnosed according to 1984 Modified New York criteria and Assessment in Spondylarthritis International Society classification criteria were included. 41 of them were receiving anti-tumor necrosis factor treatment and 33 of them were receiving nonsteroid anti-inflammatory drugs. We recorded patients' age, gender, erythrocyte sedimentation rates, C-reactive protein values, blood count, biochemical analysis, thyroid function tests, autoantibody levels, Bath Ankylosing Spondylitis Disease Activity Index.
Results: Mean anti-thyroid peroxidase levels were significant at a high level in ankylosing spondylitis patients receiving anti-tumour necrosis factor compared to patients receiving nonsteroid anti-inflammatory drugs (p= 0.009).Negative correlation was found between thyrotropin-stimulating hormone and C-reactive protein(r=-0,264, p=0,023).A positive correlation was found between free thyroxine and C-reactive protein (r=0,436,p=0,009), anti-thyroid peroxidase positivity and erythrocyte sedimentation rate (r=0,384,p=0,001),anti-thyroglobulin positivity and erythrocyte sedimentation rates and C-reactive protein(r=0,329,r=0,265,p=0,004,p=0,022).
Conclusion: The frequency of thyroid disorder in patients with AS receiving anti-TNF α was lower compared to patients receiving nonsteroid anti-inflammatory drugs. We can consider that anti-TNF α treatment could reduce autoimmune thyroid diseases and had a positive effect on thyroid functions.

Key words: Thyroid function, ankylosing spondylitis, anti-tumor necrosis factor treatment