Deficiency of serum concentration of 25-hydroxyvitamin D in psoriatic patients: A case-control study

Background: Some autoimmune conditions have been associated with reduced vitamin D levels, including systemic lupus erythematosus, rheumatoid arthritis, diabetes mellitus, and multiple sclerosis. Objective: The main objective of this study was to analyze the 25-hydroxyvitamin D (OHD) status of patients with psoriasis in comparison with control subjects without this disease. Methods: This case-control study included 86 patients (43 with psoriasis and 43 age- and sex-matched control subjects) from the outpatient clinic of our hospital dermatology department in Granada, Spain. All patients and control subjects were studied during one 4-week period to avoid seasonal variations in vitamin D levels. Results: Serum 25-OHD levels were significantly lower in psoriatic patients than in control subjects even after adjusting for confounding factors in a multivariate analysis (odds ratio 2.89, 95% confidence interval 1.02-7.64, P < .03 for vitamin D insufficiency). Low 25-OHD levels were negatively associated with C-reactive protein (inflammatory activation marker) and body mass index in multiple linear regression analysis. Psoriatic patients with body mass index greater than or equal to 27 kg/m(2) had a higher risk of 25-OHD insufficiency (sensitivity of 82.3% and specificity of 51.7%). Limitations: Further studies with larger numbers of patients are required to analyze the pathogenic mechanisms underlying the relationship between 25-OHD deficiency and psoriasis. Conclusions: The 25-OHD values are significantly lower in psoriatic patients than in control subjects. Low 25-OHD levels are negatively associated with C-reactive protein, an inflammatory activation marker, and with obesity. Psoriatic patients with a body mass index of 27 or more are likely to have vitamin D insufficiency. (J Am Acad Dermatol 2012;67:931-8.)