Abstract
Low vitamin D levels have been found in patients with autoimmune diseases, including type I diabetes, rheumatoid arthritis, multiple sclerosis and systemic lupus erythematosus. The main source of vitamin D is exposure to sunlight, but the same solar radiation is known to exacerbate lupus erythematosus. We investigated the prevalence of vitamin D insufficiency in patients with cutaneous lupus erythematosus (CLE). We designed a cross-sectional study including 55 patients with CLE to measure their serum 25-hydroxyvitamin D (25(OH)D) by chemiluminescence immunoassay and compare it with a control group consisting of 37 healthy sex and age-matched subjects recruited from the patients’ relatives as well as healthcare workers. Correlations with clinical and demographic variables were determined. Approximately 95% of patients with CLE had less than 30 ng/ml of serum 25(OH)D, which is accepted as the lower limit for vitamin D adequacy. Mean serum vitamin D values were significantly lower than controls (p = 0.038) and were associated with higher levels of parathyroid hormone (p = 0.050). A history of CLE was a strong predictor of insufficiency of vitamin D (odds ratio 4.2; 95% confidence interval 1.0—17.4). The results suggest a role of CLE in the metabolism of the vitamin and provide guidance for future studies looking at a potential role for vitamin D in the prevention and treatment of CLE. Lupus (2010) 19, 810—814.