Evidence for vitamin D deficiency and increased prevalence of fractures in autoimmune bullous skin diseases

Background Vitamin D deficiency plays a role in autoimmune diseases and risk of fractures. No data are available on vitamin D levels and vertebral fractures in autoimmune bullous skin diseases. Objectives To assess serum vitamin D levels and the prevalence of vertebral fractures in patients with pemphigus vulgaris (PV) and bullous pemphigoid (BP), potentially fatal autoimmune bullous disorders. Methods We studied 13 consecutive inpatients with untreated active PV (six men and seven women, mean ± SD age 53·5 ± 14·3 years), 15 with BP (seven men and eight women, mean ± SD age 76·9 ± 12·4 years) and 28 age-, body mass index- and sex-matched controls. The 25-hydroxyvitamin D (25-OHD) levels and presence of vertebral fractures on spinal X-ray were assessed in all subjects. Results In patients with PV, 25-OHD levels were lower (mean ± SD 12 ± 4·4 ng mL^-1) and prevalence of severe hypovitaminosis D higher (62%) than in controls (mean ± SD 22·2 ± 11·7 ng mL^-1, P = 0·012; 23%, P = 0·0047, respectively). The prevalence of fractures was 54% and 31% in patients with PV and controls, respectively. Patients with BP showed lower 25-OHD levels (mean ± SD 9·6 ± 7·2 ng mL^-1) and higher prevalence of severe hypovitaminosis D (73%) than controls (mean ± SD 22·6 ± 18·7 ng mL^-1, P = 0·022; 27%, P = 0·01, respectively). The prevalence of fractures tended to be higher in patients with BP than in controls (67% vs. 33%, respectively, P = 0·068). Conclusions The low 25-OHD levels found in PV and BP may suggest a role for this agent in their pathogenesis. The increased prevalence of fractures should be taken into consideration in patients who must be given corticosteroids.