Background: Recently, vitamin D deficiency has been implicated as a potential environmental factor triggering some autoimmune disorders, including systemic lupus erythematosus (SLE)). In addition, patients with SLE, especially those with increased disease activity, were suggested to have decreased vitamin D level, suggesting that vitamin D might play a role in regulating autoantibody production.
Material/Methods: To assess 25 hydroxy vitamin D [25(OH)D] status in Egyptian patients with SLE and its relation to disease activity. Clinical evaluation and assay of serum 25(OH)D, total calcium, phosphorous, alkaline phosphatase (ALP) and parathyroid hormone (PTH) were done on 60 SLE patients in comparison to 60 matched-healthy subjects. Serum 25(OH)D levels <30 and 10 ng/ml were defined as vitamin D insufficiency and deficiency, respectively.
Results: Serum 25(OH)D was significantly lower in patients than in controls (26.33±12.05 vs. 42.66±9.20 respectively, p<0.0001), with 13.30% and 60% being deficient and insufficient, respectively. Serum 25(OH)D levels were lower with increased disease activity (p=0.03) and frequency of photosensitivity(p=0.02) and photoprotection (p=0.002). Systemic lupus erythematosus disease activity index (SLEDAI) score (OR: 2.72, 95% CI: 1.42–5.18, P=0.002), photosensitivity (OR: 3.6, 95% CI: 1.9–6.8, P<0.01) and photoprotection (OR: 6.7, 95% CI: 2.9–8.8, P<0.001) were significant predictors of 25(OH)D level among SLE cases.
Conclusions: Low vitamin D status is prevalent in Egyptian SLE patients despite plentiful exposure to sunlight throughout the year, and its level is negatively correlated to disease activity. Future studies looking at a potential role of vitamin D in the pathophysiology and treatment of SLE are warranted.

Keywords: Photosensitivity Disorders - complications, Lupus Erythematosus, Systemic - therapy, Egypt, Child, Case-Control Studies, Bone and Bones - pathology, Adolescent, Sunlight, Vitamin D - blood, young adult