Association Between Serum Procalcitonin and Oxidative Stress in Patients with Rheumatoid Arthritis

Abstract

Background: Rheumatoid Arthritis (RA) is a chronic systemic autoimmune disorder characterised by persistent synovial inflammation of immune system overactivation and oxidative stress. Objectives: This study aimed to assess serum levels of procalcitonin and selected oxidative stress biomarkers (H₂O₂, NO and TBARS) in patients with rheumatoid arthritis, their correlation to disease severity and interrelationship in RA pathophysiology. Methods: This case–control cross-sectional study included 72 patients with clinically diagnosed RA and 88 apparently healthy controls recruited from Al-Najaf Teaching Hospital, Al-Najaf City, Iraq, during the period between May 2025 to December 2025. Based on clinical severity assessment, patients were grouped into mild, moderate and severe disease activity groups. Serum procalcitonin was assessed through enzyme-linked immunosorbent assay (ELISA), markers of oxidative stress, including H₂O₂ and NO were quantitatively assessed in serum by standard colourimetric biochemical assays; for TBARS levels, quantitative determination based on the generation of thiobarbituric acid reactive compounds was performed. Results: The levels of serum procalcitonin, H₂O₂, NO and TBARS were markedly higher in rheumatoid arthritis patients than in healthy controls (p < 0.01). There was a stepwise increase in concentration of all biomarkers with increasing disease severity, with the highest concentrations found in severe RA patients. Procalcitonin correlated positively with TBARS (P < 0.01), whereas there were positive, but not significantly different, correlations with H₂O₂ and NO, respectively. Conclusion: Serum procalcitonin and oxidative stress markers were significantly high in RA patients and elevated in parallel with the severity of the disease. The importance of the relationship between procalcitonin and TBARS indicates how inflammatory burden relates to lipid peroxidation in RA pathophysiology.