Vitamin D deficiency in patients with active systemic lupus erythematosus

We investigated the effects of disease activity on bone metabolism in 36 patients with systemic lupus erythematosus (SLE). Changes in bone remodeling were not explained by corticosteroid use. A high prevalence of 25OHD deficiency in SLE patients indicates the need for vitamin D replacement, mainly during high disease activity periods. We investigated the effects of SLE disease activity on bone metabolism, their relation to inflammatory cytokines and vitamin D levels. We performed a cross-sectional analysis of 36 SLE patients classified according to the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) in high activity (group I: 12 patients, mean age 29.6 years) or in minimal activity (group II: 24 patients, mean age 30.0 years), and compared them to normal controls (group III: 26 women, 32.8 years). Serum calcium, phosphorus, parathyroid and sex hormones, bone remodeling markers, interleukin (IL)-6, soluble IL-6 receptor (sIL-6R), IL-1, tumor necrosis factor-alpha (TNF), 25-hydroxivitamin D (25OHD), and 1,25-dihydroxyvitamin D3 were measured, plus bone mineral density. All cytokines were significantly higher in SLE groups; IL-6 could differentiate SLE patients from controls. In group I, 25OHD levels were lower (P < 0.05), which was related to the SLEDAI (R = -0.65, P < 0.001). In multiple regression analysis, the 25OHD level was associated with SLEDAI, osteocalcin and bone-specific alkaline phosphatase. The SLEDAI score was positively correlated with all measured cytokines and especially TNF (R = 0.75, P < 0.001). SLE patients demonstrated changes in bone remodeling strongly related to disease activity. A high prevalence of 25OHD deficiency was observed in SLE patients, indicating the need for vitamin D replacement.