RESUMO
Background: Recent studies point out the important role of vitamin D in the pathogenesis of many autoimmune diseases, in between psoriasis. Vitamin D regulates function of the dendritic cells, proliferation and maturation of the keratynocytes and lymphocytes T. The aim of the study was to evaluate serum vitamin D (25OHD) concentrations in psoriatic patients in the north-east of Poland and their comparison in the summer and winter period of the year. We also evaluated relationship between 25OHD concentration and disease severity, prevalence of psoriatic comorbidities and laboratory results. Material and Methods: 25OHD serum concentration was evaluated by electrochemiluminescent method in 115 patients with exacerbated plaque type psoriasis. 39 patients were evaluated in the summer and 79 in the winter time. 28 patients from winter group were treated with narrow band ultraviolet B radiation (NB-UVB). The results were compared with 38 healthy persons. Results: 25OHD serum concentrations of psoriatic patients were significantly lower than in the control group (p=0,0003). Vitamin D deficiency was diagnosed in 66% of patients in the summer time and in 63% in winter time; in the control group: 24% during the summer and 71% during the winter. After UVB phototherapy we observed reduction of skin lesions, measured as a significant decline in the Psoriasis Area and Severity Index (PASI) (p<0.001). The serum 25OHD concentration increased (p<0.001). After the treatment 65% of the psoriatic patients reached normal range of 25OHD concentration, 35% of patients were still vitamin D insufficient. We demonstrate positive correlation between increase in 25OHD and number of NB-UVB phototherapy sessions (r=0.38). Conclusions: We have observed vitamin D deficiency both in psoriatic patients and in the control group. Among psoriatic patients the praevalence of deficiency were higher than in the control group, especially during the summer months. Frequent vitamin D defficiency in the groups studied indicates the need of for its supplementation. The 25OHD serum concentrations increased after phototherapy with UVB.