A Cross-Sectional Observational Study of Serum Thyroid-Stimulating Hormone (TSH) in Rheumatoid Arthritis Patients in a Tertiary Care Hospital.

BACKGROUND: Rheumatoid arthritis (RA) is a systemic autoimmune disease frequently accompanied by thyroid dysfunction, which may influence disease activity. Occasionally, patients with RA have thyroid abnormalities. Autoimmune thyroid conditions, such as Graves' disease and Hashimoto's thyroiditis, may have a genetic propensity to occur alongside RA. This study addresses a critical knowledge gap by providing data on the prevalence and patterns of thyroid dysfunction in RA patients in South Gujarat. METHODS: This cross-sectional observational study was conducted at Government Medical College, Surat and the New Civil Hospital, a tertiary care centre in South Gujarat, India, from April 2024 to May 2025, to evaluate the association between serum thyroid-stimulating hormone (TSH) levels and RA severity. Seventy adult patients diagnosed using the European Alliance of Associations for Rheumatology (EULAR) criteria were enrolled through purposive sampling. Demographic, clinical, and laboratory data, including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid arthritis (RA) factor, anti-cyclic citrullinated peptide (CCP), and thyroid function tests, were collected. Disease activity was assessed via the EULAR criteria. RESULTS: The cohort was predominantly female (94.29%), with most participants over 40 years of age. Elevated TSH levels were observed in 29.9% of patients, with 15% showing moderate-to-severe hypothyroidism (>10 mIU/L). Significant associations were found between TSH levels and EULAR disease activity scores (χ² = 13.730, p = 0.03). Regression analysis demonstrated that higher TSH (β = 0.312, p = 0.012) independently predicted increased RA severity, whereas the RA factor had no significant impact (p = 0.746). Correlation analysis confirmed strong inverse relationships between TSH and fT4 (r = -0.626, p < 0.001). CONCLUSION: These findings indicate that thyroid dysfunction, particularly hypothyroidism, is common in RA and may exacerbate disease severity. Routine thyroid function screening should be considered to optimize management and improve patient outcomes.