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 the Iranian population and determine its association with SLE disease
activity index (SLEDAI), sun exposure, smoking, photosensitivity, sun protector cream use, and drug regimen. In this crosssectional study, 200 patients were included. The patient’s data were obtained using a questionnaire. The enzyme-linked
immunosorbent assay (ELISA) technique was used to determine Vitamin D level in the serum samples of the patients. The study
population was comprised of 27 (13.5%) males and 173 (86.5%) females, with a mean age of 38.46 ± 13.24 years. The 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. Vitamin D is
involved in the disease activity of SLE patients. It is important to include vitamin D supplementation in the drug regimen of SLE
patients, especially when it includes glucocorticoids.