AUTOIMMUNE OVERLAP SYNDROME: IMMUNOPATHOLOGICAL, CLINICAL AND CARDIOVASCULAR IMPLICATIONS OF COMORBID RHEUMATOID ARTHRITIS AND AUTOIMMUNE HYPOTHYROIDISM
Keywords:
Rheumatoid arthritis, Hashimoto’s thyroiditis, autoimmune hypothyroidism, cytokines, DAS28, systemic inflammation, cardiovascular risk, immune dysregulationAbstract
Background: Rheumatoid arthritis (RA) and autoimmune hypothyroidism (AH), predominantly Hashimoto’s thyroiditis, are chronic immune-mediated disorders with overlapping genetic susceptibility and inflammatory mechanisms. Increasing epidemiological evidence indicates that their coexistence is more frequent than expected by chance.
Objective: To comprehensively analyze the epidemiology, shared immunopathogenesis, clinical expression, cardiovascular burden, and therapeutic implications of RA and autoimmune hypothyroidism comorbidity.
Methods: A structured review of cohort studies, case-control analyses, immunological investigations, and translational research was conducted to evaluate prevalence rates, cytokine profiles, autoantibody patterns, metabolic alterations, and cardiovascular outcomes in patients with RA and concomitant thyroid dysfunction.
Results: RA patients demonstrate a significantly increased prevalence of autoimmune hypothyroidism (10–30%) compared to the general population. Shared mechanisms include HLA-DRB1 susceptibility alleles, PTPN22 polymorphism, T-cell dysregulation, B-cell hyperactivity, and chronic overexpression of TNF-α and IL-6. Hypothyroidism contributes to amplified systemic inflammation, dyslipidemia, endothelial dysfunction, and increased cardiovascular morbidity. Thyroid dysfunction may also alter RA disease activity indices and therapeutic responsiveness.
Conclusion: The coexistence of RA and autoimmune hypothyroidism represents a clinically significant autoimmune overlap syndrome. Integrated screening and multidisciplinary management are essential to reduce systemic complications and optimize long-term outcomes.
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