Vitamin D deficiency and its association with disease activity in new cases of systemic lupus erythematosus.

Evidence has shown a relationship between vitamin D deficiency and systemic lupus erythematosus (SLE). We evaluated the frequency of vitamin D deficiency and its association with disease activity in new cases of SLE. Women with newly diagnosed SLE, based on the American College of Rheumatology (ACR) criteria, were enrolled consecutively. Those receiving vitamin D supplements and postmenopausal women were not included. Disease activity was measured by the BILAG index (2004) and serum concentration of 25-hydroxyvitamin D (25[OH]D) was measured by radioimmunoassay method. Forty SLE patients with mean age of 25.3 ± 4.2 years were studied. Severe, moderate, and mild vitamin D deficiency, corresponding to serum 25[OH]D concentrations of <12.5, 12.5-24.9, and 25-39.9  nmol/l, were found in 12.5%, 62.5%, and 17.5% of the patients, respectively. Serum 25[OH]D concentration was inversely correlated with the British Isles Lupus Assessment Group (BILAG) index score (r = -0.486, p = 0.001). Those with a more severe vitamin D deficiency had also higher concentrations of liver enzymes (p < 0.05), lower serum albumin and hemoglobin concentrations (p < 0.05), and higher titers of antibodies to double-stranded DNA (ds-DNA) (p < 0.001). This study showed that most of the SLE patients in our society have vitamin D deficiency at the time of diagnosis that is associated with a higher disease activity. Routine screening for vitamin D deficiency and its prompt treatment in patients with newly diagnosed SLE is recommended.