Serum Vitamin D Level and Disease Activity in Patients With Systemic Lupus Erythematosus

INTRODUCTION: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with variable clinical manifestations and disease activity. Emerging evidence suggests that vitamin D may play a role in immune regulation and disease pathogenesis. This study aimed to investigate the association between serum vitamin D levels and disease activity in patients with SLE at Mandalay General Hospital. METHODS: A cross-sectional study was conducted involving 60 patients diagnosed with SLE. Disease activity was assessed using the Systemic Lupus Activity Measure (SLAM) score. Serum vitamin D levels were measured using the enzyme-linked immunosorbent assay (ELISA) at the National Health Laboratory, Mandalay. Patients were categorized into active and inactive disease groups based on SLAM scores, and intergroup comparisons were made. RESULTS: Among the 60 patients, the majority (43.3%) were aged 21-30 years, with a mean ± SD age of 25.77 ± 7.98 years. Female patients predominated (98.3%; female-to-male ratio 59:1). The mean SLAM score was 9.25 ± 2.94. Common clinical features included anaemia (56.7%), skin rash (33.3%), mucosal ulcers (16.7%), arthritis (16.7%), serositis (11.7%), vasculitis (11.7%), and neuropsychiatric lupus (5%). Patients with active disease had significantly lower serum vitamin D levels (12.2 ± 1.36 ng/mL) compared to those with inactive disease (26.1 ± 10.22 ng/mL; t = 5.55, p < 0.0001). A moderate inverse correlation was observed between SLAM scores and vitamin D levels (Pearson's r = -0.51, p < 0.0001), suggesting a clinically meaningful association between lower vitamin D levels and higher disease activity. CONCLUSION: This study demonstrates a moderate inverse relationship between serum vitamin D levels and SLE disease activity. These findings suggest that vitamin D may serve as a potential biomarker for disease monitoring. However, due to the cross-sectional design and relatively small sample size, causality cannot be established. Further longitudinal studies are recommended.