RESUMO
BACKGROUND: Chronic urticaria is a common distressing allergic skin disorder. Immune dysregulation, histamine release and mast cell degranulation are suggested as its underlying mechanisms. OBJECTIVE: Add-on therapy of vitamin D was evaluated in patients with chronic spontaneous urticaria to determine the quality of life and urticaria severity score. METHODS: In a prospective, double-blinded study, 80 participants with chronic spontaneous urticaria were randomized to low (4200 IU/week, group 1) and high (28,000 IU/week, group 2) vitamin D3 supplementation groups for 12 weeks. Demographic data; quality of life, urticaria severity and medication scores; 25-hydroxyvitamin D and anti-thyroid peroxidase antibody levels; and autologous serum skin test data were collected. RESULTS: Both groups showed significantly reduced total urticaria severity score; decrement in group 2 score was significant compared to group 1 at week 6 (P = 0.010). Quality of life score was also significantly reduced; decrement in group 2 score was significant compared to group 1 at both weeks 6 (P = 0.005) and 12 (P = 0.007). 25-hydroxyvitamin D levels were elevated significantly over the course of 12 weeks in both groups; however, the elevation in group 2 was significantly higher than group 1 at week 12 (P = 0.002). Medication score was significantly reduced, with no significant difference between groups. No association was observed between positive autologous serum skin test, angioedema and high level of Anti thyroperoxidase antibody with positive response to vitamin D. CONCLUSIONS: Add-on therapy with vitamin D (28,000 IU/week) can be considered as a safe and potentially beneficial treatment in patients with chronic spontaneous urticaria.