Background: Vitamin D level varies according to the geographic location. This study was conducted to evaluate Vitamin D level in the serum samples of Systemic lupus erythematosus (SLE) patients from Iranian population and determine its association with SLE disease activity index (SLEDAI), sun exposure, smoking, photosensitivity, sun protector cream use, and drug regimen.
Methods: In this cross-sectional study, 200 patients were included. The patient’s data were obtained using questionnaire. The enzyme-linked immunosorbent assay (ELISA) technique was used to determine Vitamin D level in the serum samples of the patients.
Results: The study population was comprised of 27 (13.5%) males and 173 (86.5%) females, with mean age of 38.46 ± 13.24 years. Serum level of Vitamin D was 13.62 ± 3.22 ng/ml in the patients. Vitamin D deficiency was observed in 104 (52%) patients. There was a statistically positive correlation between vitamin D level and duration of sun exposure (CC= 0.57, P= 0.004). A statistically significant negative correlation was seen between vitamin D level and SLEDAI (CC= -0.41, P= 0.013). Vitamin D level was significantly (P= 0.030) lower in the SLE patients with photosensitivity. SLE patients using sun protector cream had significantly (P= 0.002) lower level of Vitamin D. Patients receiving glucocorticoid drugs, had significantly (P= 0.001) lower levels of Vitamin D in comparison to the patients not receiving glucocorticoids.
Conclusions: Vitamin D is involved in the disease activity of SLE patients. It is important to include vitamin D supplementation in drug regimen of SLE patients, especially when it includes glucocorticoids.