Níveis séricos de vitamina D em pacientes com lúpus eritematoso sistêmico: associação com nefrite lúpica, atividade da doença e densidade mineral óssea

Abstract

Currently, it is described an immunomodulator role of vitamin D besides its already known effect on bone homeostasis. Vitamin D insufficiency is considered to be epidemic and may influence the pathogenesis of autoimmune diseases, like Systemic Lupus Erythematosus (SLE). This study evaluated the prevalence of vitamin D insufficiency in patients with SLE compared to healthy controls, and the association between vitamin D and clinical parameters, lupus nephritis, disease activity and bone mineral density (BMD). Vitamin D was evaluated by serum analysis of 25-hydroxyvitamin D [25(OH)D] by high performance liquid chromatography (HPLC) and levels below 30 ng/mL were considered insufficient. We evaluated 45 patients with SLE and 25 healthy controls. Median (range) of 25(OH)D was 29,48 (20,83-44,23) ng/mL in lupus patients and 37,68 (22,91-44,07) ng/mL in controls (p<0,0001). The prevalence of 25(OH)D insufficiency was 55% in patients and 8% in controls (p=0,001). Vitamin D was associated with time of disease duration (r=0,311; p=0,037) and use of hydroxychloroquine (HXQ) (r=-0,337; p=0,024). There was a weak evidence of inverse association between vitamin D and interleukin (IL)-6 in patients with SLE (r=-0,276; p=0,066). No association between 25(OH)D and lupus nephritis or bone mineral density was found. Multivariate logistic regression analysis evidenced higher probability of 25(OH)D < 30 ng/mL in SLE patients than in controls (OR: 78,25; p=0,0001), when adjusted to possibly confounding variables. In lupus patients, hypovitaminosis D was prevalent. Vitamin D was associated with time of disease duration and use of hydroxychloroquine.