Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 14 2 2015 04 15 222 227 EN Masoud Movahedi Department of Allergy and Clinical Immunology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. Marzieh Tavakol Department of Allergy and Clinical Immunology, Shahid Bahonar Hospital, Alborz University of Medical Sciences, Karaj, Iran. Armin Hirbod-Mobarakeh Molecular Immunology Research Center, Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran AND Students’ Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Gharagozlou Department of Allergy and Clinical Immunology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. Asghar Aghamohammadi Department of Allergy and Clinical Immunology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran AND Research Center for Immunodeficiencies, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran. Zahra Tavakol Student' Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran. Kaveh Momenzadeh Students' Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Nabavi Department of Allergy and Immunology, Rasool-e-Akram Hospital, Iran University of Medical Sciences, Tehran, Iran. Abbas Dabbaghzade Department of Allergy and Clinical Immunology, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. Asieh Mosallanejad Imam Hosein Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Nima Rezaei Molecular Immunology Research Center, Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran AND Research Center for Immunodeficiencies, Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran. 2015 10 16 Chronic urticaria is the most common skin diseases, characterized by chronic cutaneous lesions which severely debilitates patients in several aspects of their everyday life. Vitamin D is known to exert several actions in the immune system and to influence function and differentiation of mast cells, central role players in the pathogenesis of chronic idiopathic urticaria. This study was performed to evaluate the relationship between vitamin D levels and susceptibility to chronic idiopathic urticaria. One hundred and fourteen patients with chronic idiopathic urticaria were recruited in this study along with one hundred and eighty seven sex-matched and age-matched healthy volunteers as the control group. For each patient, urticaria activity score was calculated and autologous serum skin test was done. Vitamin D metabolic statue was measured in serum as 25 hydroxyvitamin D using enzyme immunoassay method. Patients with chronic idiopathic urticaria significantly showed lower levels of vitamin D. Vitamin D deficiency was significantly associated with increased susceptibility to chronic idiopathic urticaria. There was a significant positive correlation between vitamin D levels and urticaria activity score. This study showed that patients with chronic idiopathic urticaria had reduced levels of vitamin D, while vitamin D deficiency could increase susceptibility to chronic idiopathic urticaria. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/391 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/391/446