Background and aims Vitamin D has numerous effects on cells within the immune system. Association between vitamin D deficiency and high disease activity in systemic lupus was confirmed. The aim of this research was to study the effect of vitamin D therapy on urinary angiostatin as a marker of activity in juvenile lupus.

Methods Fifty female patients with juvenile systemic lupus erythematosus (SLE) were enrolled in this study for twelve weeks trial of high dose of oral vitamin D weekly. We used radioimmunoassay to measure Serum levels of vitamin D. Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and the European Consensus Lupus Activity Measurement (ECLAM) were measured to assess lupus activity. Urinary angiostatin was evaluated as marker of activity. All parameters were measured on the day one of study and after three months. Thirty juvenile SLE patients as control.

Results At beginning of study all patients and control were almost similar regarding age, clinical, laboratory, urinary angiostatin and vitamin D levels. After three months the mean Vitamin D level was increase in patients group received Vitamin D than in control group (p<0.001). There was significant decrease in urinary angiostatin (p<0.05) was observed in the patients received vitamin D compared to patient without vitamin D supplementation.

Conclusions Our findings show that high dose of vitamin D supplementation up to 12 weeks is safe and diminish lupus activity. We need longer duration and more studies to confirm our results.