Background and aims: : Systemic lupus erythematosus (SLE) is an autoimmune disease which involves
various organs. Vitamin D is an essential ingredient in regulating the immune system. This study aimed
to investigate the relationship between vitamin D and the severity of lupus activity.
Materials and Methods: This case-control study was carried out on 38 patients with lupus on the basis
of the American College of Rheumatology (ACR) criteria and 44 healthy subjects with no history of
rheumatologic disease. To measure the level of 25-hydroxy vitamin D, venous blood samples (5 cc)
were taken from each participant and the activity of the lupus disease was measured by the Systemic
Lupus Erythematosus Disease Activity Index (SLEDAI) scale. Finally, the chi-square test, independent
sample t test, one-way ANOVA, and multiple linear regression analysis were used to measure
multivariate effects. The level of significance was set to be P < 0.05.
Results: Thirty-five lupus patients and 40 healthy subjects were females (P = 0.847). Vitamin D
deficiency was observed in the case (42.1%) and control (11.4%) groups. The mean value of serum
vitamin D3 level was 35.3 ng/mL in the control group, as well as 24.6 ng/mL and 21.3 ng/mL in
patients with mild and severe SLE, respectively (P = 0.024).
Conclusion: In this study, high levels of 25-hydroxy vitamin D were observed among the healthy
subjects compared to patients with SLE. Eventually, the level of vitamin D significantly decreased by
increasing the severity of SLE activity.