Hypothyroidism and autoimmune thyroid disorders in rheumatoıd arthritis: relationship wıth disease activity

Abstract

Background and aims: Thyroid function abnormalities and thyroid autoantibodies have previously been described in rheumatoid arthirits (RA) with limited data. In some studies, a relationship was found between thyroid autoantibodies and RA disease activity. However, there are not strong studies in the literature indicating the relationship between thyroid diseases and RA. The aim of this study was to determine the frequency of hypothyroidism and to investigate the relationship between thyroid hormone levels, autoantibodies and disease activity in patients with rheumatoid arthritis (RA). Methods : 1017 patients with the diagnosis of RA were recruited. This observational study was conducted between January 2014 and July 2015. Demographic variables were recorded. Anti-nuclear antibodies (ANA), anti-cyclic citrulli-nated peptide antibody (anti-CCP), Rheumatoid Factor (RF), C reactive protein (CRP), Erythrocyte Sedimentation Rate (ESR), thyroid stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), anti-microsomal antibody (anti-TPO )and anti-thyroglobulin antibody (anti-TG) were determined. Visual analog score and Disease Activiy Score 28 (DAS-28) ESR and DAS-28 CRP were recorded. The relationship between thyroid hormone levels and thyroid antibodies and disease activity parameters were determined. Results: 98 (%9,7) patients had hypothyroidism and 61 (%6) patients had hyperthyroidism. 210 (20,7%) patients with RA was positive for TPOAb and 165(16,3%) for anti-TG. Positive correlation was detected between anti-TPO positivity and anti-CCP levels (p:0.005, r:0,274). In anti-TG antibody positive patients, there was a significant positive correlation of thyroid hormone levels with CRP and DAS 28-CRP (p:0.01, r:0,120; p:0.01, r:0,169). Conclusion: Thyroid autoantibodies were found to be positive in 16-21% of patients with RA. Though hypothyroidism is not very frequent in RA patients, autoimmune thyroid disease is quite common, which may be related to disease activity.

Keywords: Disease Activity Score; autoantibodies; autoimmune thyroid disease; hypothyroidism; rheumatoid arthritis.