A study on the role of calcium homeostasis and vitamin D deficiency in premenopausal systemic lupus erythematosus patients and its relation with disease activity

Introduction Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disorder that may affect multiple organ systems. Vitamin D levels and its role in lupus inflammation is still a matter of debate. Objective The aim of this study was to assess the role of calcium homeostasis and vitamin D deficiency in premenopausal SLE patients and its relation with disease activity. Patients and methods We assessed serum 25-hydroxyvitamin D [25(OH)D] level in 60 (SLE) patients and 20 age and sex-matched healthy controls. We also assessed different clinical, immunological, and laboratory disease parameters in SLE patients − namely, erythrocyte sedimentation rate, C-reactive protein, antinuclear antibody, antidouble stranded DNA, C3, and C4–and disease activity score using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score. We correlated serum 25(OH)D with disease activity and different environmental parameters that might affect 25(OH)D level. Results A significantly lower 25(OH)D level was found in SLE patients compared with controls (P=0.033). Serum 25(OH)D was inversely correlated to SLEDAI score (P=0.043), antidouble stranded DNA (P<0.001), and erythrocyte sedimentation rate (P<0.001), but directly correlated to C3 and C4 levels (P=0.029). There was an inverse correlation between vitamin D supplementation and SLEDAI score (MCP=0.030), but there was no significant correlation with both calcium supplementation (P=0.861) and ionized calcium (P=0.681). Conclusion Vitamin D insufficiency and deficiency is highly prevalent in SLE patients than in healthy controls, and is prevalent among SLE patients with higher disease activity, which suggests an important role of vitamin D3 in the pathogenesis of SLE disease activity and flares. The therapeutic effect of vitamin D in SLE should be further assessed in interventional studies.