[Serum levels of vitamin D in systemic lupus erythematosus patients (SLE) and their relationship with disease activity: longitudinal study]. / Niveles séricos de vitamina D en pacientes con lupus eritematoso sistémico (LES) y su asociación con la actividad de la enfermedad: estudio longitudinal.

OBJECTIVE: To determine changes over time of serum levels of 25-hydroxy vitamin D (25(OH)D) in Mexican patients with SLE and their relationship with disease activity. MATERIALS AND METHODS: Longitudinal and observational study. Women with SLE were included. Serum levels of 25(OH)D were measured at baseline and after two years; the disease activity was measured with MEX-SLEDAI. Patients with initial suboptimal levels of 25(OH)D received supplements or increased doses of calcitriol. RESULTS: 105 women with SLE were included, mean age 49.4 ± 11 years. Serum levels of 25(OH)D were higher at two years (baseline 20 ± 6.8 vs. follow-up 22.7 ± 7.7; p = < 0.001). There were no differences between disease activity scores at baseline and two years (baseline 1.7 ± 1.9 vs. follow-up 1.1 ± 1.7; p = 0.7). Serum levels of 25(OH)D did not correlate with disease activity during the follow up, p = 0.7. No correlation was found between changes in MEX-SLEDAI scores and serum levels of 25(OH)D, p = 0.87. CONCLUSION: Mexican women with SLE had increased serum levels of 25(OH)D. No correlation between serum levels of 25(OH)D and disease activity was found.