Anti-thyroid peroxidase antibodies in rheumatoid arthritis patients, impact on disease activity and joint affection detected by musculoskeletal ultrasound

Background Rheumatoid arthritis is a systemic autoimmune disease characterized by extra-articular symptoms and inflammatory arthritis. Prolonged joint inflammation leads to cartilage and bone loss. Among autoimmune diseases, autoimmune thyroid disease is more common than any other. Its serological, clinical, and genetic features are comparable to those of RA. This study aimed to examine the impact of anti-thyroid peroxidase (anti-TPO) antibodies on RA disease activity and joint involvement. Methods One hundred patients with rheumatoid arthritis were included. Clinical and laboratory data were assessed. RA disease activity was assessed using the 28-joint Disease Activity Score (DAS 28), musculoskeletal ultrasound of bilateral wrists, second and third metacarpophalangeal joints (to detect synovial hypertrophy, and power Doppler signals) using the EULAR-OMERACT (European League Against Rheumatism—Rheumatology Outcome Scale) combined score. Antithyroid peroxidase antibodies were also assessed. Results Thyroid peroxidase levels were significantly positively correlated with age, disease duration, erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, anti-cyclic citrullinated peptide, ultrasound findings, DAS28, tender joint count, and swollen joint count, whereas TPO levels were negatively correlated with thyroid-stimulating hormone, triiodothyronine and tetraiodothyronine, and complete blood count. Conclusions Anti-TPO antibodies and thyroid autoimmune antibodies were more common in RA patients with more severe disease activity based on DAS28 and joint synovitis demonstrated by musculoskeletal ultrasound.