Evaluation of association of vitamin D in alopecia areata: A case–control study of 100 patients in a tertiary rural hospital of Southern India

Background: Alopecia areata is a common autoimmune disorder which is characterized by non-scarring hair loss. Vitamin D plays an important role in immune regulation, cell growth, differentiation, and maintenance of hair cycle. Aims and Objectives: (1) To evaluate serum vitamin D levels in alopecia areata. (2) To compare serum vitamin D levels in new versus old cases and with respect to severity of alopecia areata. Materials and Methods: A retrospective case–control study with 100 cases of alopecia areata and 100 age- and sex-matched healthy controls was conducted from December 2014 to November 2015. All subjects underwent complete clinical evaluation and serum vitamin D levels. Results: The mean serum vitamin D level was significantly lower in patients with alopecia areata (18.90 ± 8.32 ng/mL) (64%) as compared to healthy controls (28.21 ± 18.32 ng/mL) (38%) (P < 0.001). The mean serum vitamin D levels was significantly lower in old cases (15.11 ± 4.75 ng/mL) as compared to new cases (20.85 ± 9.09 ng/mL) (P < 0.001). The proportion of subects with vitamin D deficiency was significantly higher among old cases (84.3%) as compared to new cases (53.1%) (P < 0.05). There was a significant inverse correlation between Severity of Alopecia Tool scores and serum vitamin D levels (r = −0.298, P < 0.05). Conclusion: Decreased vitamin D levels were observed in patients with alopecia areata and significant inverse correlation exists between vitamin D levels and duration/severity of the disease. These findings may suggest a causal role of vitamin D deficiency in the pathogenesis and therapeutic role of vitamin D supplementation in the management of alopecia areata