Serum Ferritin, Vitamin D, and Vitamin B12 Levels and Their Relationship with Disease Activity in Patients with Rheumatoid Arthritis
Aim: To evaluate the associations of serum ferritin, vitamin D, and vitamin B12 levels with disease activity measured by the Disease Activity Score 28-C-Reactive Protein (DAS28-CRP) and to compare these biomarkers between controls and patients with RA receiving conventional disease-modifying antirheumatic drugs (DMARDs) or biologic therapy. Materials and Methods: This retrospective cross-sectional study included 109 patients with RA (77 receiving conventional DMARD therapy and 32 receiving biologic therapy) and 24 controls. Demographic, clinical, treatment-related, and laboratory data were retrieved from the hospital information management system. Serum ferritin, vitamin D, vitamin B12, and folate levels were compared among the groups using the Kruskal–Wallis test. Correlations between DAS28- CRP and laboratory variables were evaluated using Spearman’s rank correlation analysis. Results: Serum ferritin and vitamin B12 levels were comparable among the three groups (both p > 0.05). In contrast, serum vitamin D levels differed significantly, with higher concentrations in both RA treatment groups than in controls (p = 0.029). No significant correlations were observed between DAS28-CRP and serum ferritin (r = 0.001, p = 0.991), vitamin D (r = -0.104, p = 0.280), or vitamin B12 (r = 0.065, p = 0.502). Conclusion: Serum ferritin, vitamin D, and vitamin B12 levels were not associated with disease activity in patients with RA. Although vitamin D levels were higher in treated patients, likely reflecting routine supplementation, none of these biomarkers appeared to be a reliable surrogate marker of disease activity. Keywords: Rheumatoid arthritis, Ferritin, Vitamin B12, Vitamin D, Disease activity.