Association of Serum Vitamin D and Ferritin Levels with Disease Activity in Patients with Rheumatoid Arthritis

Abstract

Objective: This study aims to study association of serum vitamin d and ferritin levels with disease activity in patients with rheumatoid arthritis.

Methodology: 89 adult patients with rheumatoid arthritis fulfilling the 2010 ACR/EULAR classification criteria were included. Demographic and clinical data, including disease duration, medication history, tender and swollen joint counts, ESR, and CRP, were recorded. Disease activity was assessed using the Disease Activity Score-28 (DAS28). Fasting venous blood samples were obtained for measurement of serum 25-hydroxyvitamin D and ferritin using standardized immunoassay methods. Patients were categorized according to DAS28 disease-activity levels. Statistical analysis included descriptive statistics, correlation analysis, and multivariable regression. Pearson's or Spearman's correlation was used to assess associations between vitamin D, ferritin, and DAS28. A p-value <0.05 was considered statistically significant.

Study Design Duration: 06 months from March 2026 to August 2026.

Results: Among 89 patients, mean age was 45.8 ± 10.7 years and 75.3% were female. Mean vitamin D and ferritin levels were 19.6 ± 7.8 ng/mL and 286.4 ± 174.7 ng/mL, respectively. Vitamin D deficiency was present in 61.8% patients. Moderate-to-high disease activity was observed in 73.0%. Vitamin D demonstrated a significant inverse correlation with DAS28 (r = −0.46, p <0.001), whereas ferritin showed a significant positive correlation (r = 0.52, p <0.001). Vitamin D and ferritin remained significantly associated with DAS28 after adjustment for age, sex, and disease duration.

Conclusion: Lower vitamin D and higher ferritin levels were significantly associated with greater rheumatoid arthritis disease activity.