Original paper
Requirement of vitamin D supplementation in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease. Most SLE patients are sensitive to ultraviolet radiation (UV), which exacerbates the course of the disease. Therefore photoprotection is recommended management in all subjects.
Aim of the study: To investigate serum concentration of 25(OH) vitamin D3 in patients with SLE, and elucidate the association between vitamin D level and disease activity, pharmacotherapy, and selected risk factors for vitamin D deficiency.
Material and methods: 48 patients with SLE (44 females and 4 males) were examined. The diagnosis was established based on ACR criteria and disease activity was assessed with SLAM score. Serum concentration of 25(OH)D3 was measured with automated electrochemiluminescence immunoassay platform Elecsys 2010 (Roche Diagnostic GmbH) under the DEQAS control system.
Results: Mean serum concentration of 25(OH) vitamin D3 in SLE patients was 11.99±7.98 ng/ml. In 47 (97.91%) patients concentration of 25(OH)D3 was lower than the recommended level (<30 ng/ml), including hypovitaminosis in 2 (4.16%), and deficiency/deficit (<20 ng/ml) in 45 (93.75%) patients. Serum 25(OH)D3 concentrations measured during the cold period of the year (between 5th October and 5th April) were significantly decreased in comparison with those measured in the warm period (between 5th April and 5th October) (p=0.009). Furthermore, the cold period of the year was found to be a risk factor of vitamin D deficiency (<20 ng/ml) (OR=10.14; p<0.05). No association was found between serum 25(OH) vitamin D3 concentration and age, gender, body mass, height, BMI, II and III skin phototype, disease duration and activity, antimalarials and glucocorticoids therapy.
Conclusions: The obtained results confirm vitamin D deficiency in SLE patients, and increase the need of effective vitamin D supplementation.